How to forward declare variables in Python

I would like to know how to forward declare variables in Python. I have attached a program here. Please if anyon e has time please look at it. It is a pizza ordering program. SGST and CGST are taxes in my country. I have added the taxes to the final price and it is printing the final price as well. But I want to print SGST & CGST individually ( CGST = SGST = 2.5% of final price ). Please help me if you know.

CGST = 0.025
SGST = 0.025

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def displaypizzalist(): 

    print("\n************************************PIZZA MENU***************************************")

    print((("_")*90)+"\n") 


    for i in range(0,7): 

        print("\t|\t" +str(i+1) + ". \t" + str(pizzasale[0][i]) + "\t" +"Rs "+str("{:0.2f}".format(pizzasale[1][i])))

        print((("_")*90)) 

def removeorder(order): 

    if order == False: 

        completeorder = -1

    else:

        completeorder = ordernumber.index(order) 

      
    ordernumber.pop(completeorder) 

    orderpizzatype.pop(completeorder) 

    orderpizzaprice.pop(completeorder)

    orderpizzanum.pop(completeorder)

    ordertotalcost.pop(completeorder)

    orderdelivery.pop(completeorder)

    orderaddress.pop(completeorder)

    orderphone.pop(completeorder)

    if order == False: 

        print("\nORDER CANCELLED")

        global ordercounter

        ordercounter-=1 




def displayorders(allorders): 

    if allorders ==True:

        print("\nUNCOMPLETED ORDERS")

        maxorder = len(ordernumber)+1 

    else:

        print("\nDETAILS FOR LAST ORDER") 

        maxorder = 2 

    print((("_")*90)) 
    for i in range (1,maxorder): 
        print("\n\t|\tORDER NO. " + str(ordernumber[-i]))

        if orderdelivery[-i]==True: 

            print("\t|\tTHE ORDER IS FOR DELIVERY ")

            print("\t|\tNAME: \t\t" + ordername[-i])

            print("\t|\tADDRESS: \t" + orderaddress[-i])
            print("\t|\tPHONE NO: \t" + orderphone[-i]) 
        else:

            print("\t|\tTHE ORDER IS FOR PICKUP ")

            print("\t|\tNAME: \t" + ordername[-i]) 
        print("\t|\n\t|\tPIZZAS ORDERED: ") 

        for ii in range(0,(orderpizzanum[-i])): 

            print("\t|\t" +str(ii+1) + ". \t" + str(orderpizzatype[-i][ii]) + "\t\t"+"Rs "+ str("{:0.2f}".format(orderpizzaprice[-i][ii])))





        if orderdelivery[-i]==True:
            print("\t|\t\tDelivery Charge:\t\tRs 40")

                 
        print("\t|\t\tGST:\t\t\t"  )

        print("\t|\t\t\tCGST(2.5%):\tRs.")
              

        print("\t|\t\t\tSGST(2.5%):\tRs.")

        
        
        print("\n\t|\t\tTOTAL ORDER COST :\tRs " + str("{:0.2f}".format(ordertotalcost[-i]))) 

        print((("_")*90)) 
pizzasale = [["Margretta.\t","Cheesy.\t\t","Mexican.\t","Veggie\t\t","Mushroom.\t","Italiano.\t","Farmhouse\t"],[125,195,205,225,255,285,345]] 

delivery = 40
codeone=100

codetwo=150

ordercounter = 0 

ordercoupon=[]

ordernumber = []

orderdelivery = []
ordername = [] 
ordertotalcost = [] 
orderphone = [] 
orderaddress = [] 
orderpizzatype = [] 
orderpizzanum = [] 
orderpizzaprice = [] 
ordering=True 


while True:

              
    
    while ordering==True:

        ordercounter += 1 
        ordernumber.append(ordercounter) 
        orderpizzatype.append([],)
        orderpizzaprice.append([],)
        print(' ---------------------------------------------------------------------------------')
        print("\nNEW ORDER\n")

        deliverytemp = str(raw_input("DO YOU WANT YOUR PIZZA TO BE DELIVERED ? Y/N : ")).lower().strip()
        if deliverytemp=="y" or deliverytemp=="yes": 
           
            orderdelivery.append(True) 
            ordertotalcost.append(float(0))

        else:

            orderdelivery.append(False) 

            ordertotalcost.append(float(0)) 

        nametemp = str(raw_input("ENTER YOUR NAME\t\t\t             : ")) 
        ordername.append(nametemp) 

        if orderdelivery[-1] == True: 
            phonetemp = str(raw_input("ENTER YOUR CONTACT NUMBER\t\t     : "))
            orderphone.append(phonetemp) 

            addresstemp = str(raw_input("ENTER YOUR DELIVERY ADDRESS\t\t     : ")) 

            orderaddress.append(addresstemp) 

        else: 

            orderphone.append(False)
            orderaddress.append(False) 
        integermarker= False 
        
        while integermarker == False:

            pizzanumtemp = (raw_input("HOW MANY PIZZA DO YOU WANT( max upto 10)     : ").strip()) 
            try:
                pizzanumtemp=int(pizzanumtemp)
                if pizzanumtemp<11 and pizzanumtemp>0: 
                    orderpizzanum.append(pizzanumtemp) 
                    integermarker = True 
                else: 
                    raise ValueError 
                    
            except ValueError or TypeError:
                print("'"+str(pizzanumtemp)+ "' IS NOT A WHOLE NUMBER IN 1 TO 7,PLZZ  TRY AGAIN.\n") 
        displaypizzalist()
        for i in range (0,orderpizzanum[-1]): 
            integermarker= False
            
            while integermarker == False: 
                pizzatemp = (raw_input("\nENTER THE CORRESPONDING PIZZA CODE FROM THE PIZZA MENU " + str(i+1) + " / " + str(orderpizzanum[-1]) + ": ").strip())
                try: 
                    pizzatemp = int(pizzatemp)
                    if pizzatemp > 0 and pizzatemp < 8:
                        orderpizzatype[-1].append(pizzasale[0][pizzatemp-1])
                        orderpizzaprice[-1].append(pizzasale[1][pizzatemp-1])
                        GST = float((CGST + SGST)*((pizzasale[1][pizzatemp-1])))
                        
                        ordertotalcost[-1] += float(GST + (pizzasale[1][pizzatemp-1]))
                        integermarker = True
                    else: 
                        raise ValueError
            

                except ValueError or IndexError or TypeError: 
                    print("'"+str(pizzatemp)+ "'IS NOT A VALID SELECTION,PLZZ TRY AGAIN.       : ") 
        displayorders(False) 
        ordercorrect=str(raw_input("\nIS THE ORDER CORRECT? Y/N                      : ")).lower().strip()
        print ordertotalcost[-1]
        GST1 = float((CGST + SGST) * (ordertotalcost[-1] - GST ))
        print ordertotalcost[-1]
        print GST1
    
        if ordercorrect=="n" or ordercorrect=="no": 
            removeorder(False) 
        else: 
            ordering=False
        
        



            while True and ordertotalcost[-1] > 250:
                print"\n"
                print"Default coupon codes : pizza100, pizza150"
                x=(raw_input("DO YOU HAVE ANY COUPON CODE ? Y/N              : ")).strip()
                if x.upper()=="Y":
                    z= str(raw_input("\nWHAT IS YOUR COUPON CODE                       : "))
                    while z == "pizza100" or z == "pizza150":
                        if z=="pizza100":
                            print("\nYOU'R 100 Rs WILL BE DISCOUNTED FROM YOUR TOTAL AMOUNT")

                            ordertotalcost[-1] = ordertotalcost[-1] - 100
                            test = ordertotalcost[-1]
                            break
                            
                        elif z=="pizza150":
                            print("\nYOU'R 150 Rs WILL BE DISCOUNTED FROM YOUR TOTAL AMOUNT")
                            ordertotalcost[-1] = ordertotalcost[-1] - 150
                            test = ordertotalcost[-1]
                            break
                            
                        else:
                            print("\nINVALID COUPON CODE.")
                            y=str(raw_input("\nDO YOU WANT TO ENTER THE CODE AGAIN ? Y/N        : ")).strip()
                            if y=="y" or y=="yes":
                                continue
                            else :
                                break
                        
                    break
                break
            else:
                print" Coupon not applicable on pizzas below Rs. 250 "
            ordering = True
            

            
                
            displayall = str(raw_input("\nWOULD YOU LIKE TO DISPLAY ALL YOUR ORDERS? Y/N : ")).lower().strip()
            while displayall == "y" or displayall == "yes": 
                displayorders(True) 
                    
                completeorder = str(raw_input("\nDO YOU WANT TO COMPLETE THE ORDER? Y/N         : ")).lower().strip()
                if completeorder == "y" or completeorder == "yes":
                    integermarker= False

                    while integermarker == False: 
                        ordertocomplete = (raw_input("\nWHICH ORDER DO YOU WANT TO MARK AS COMPLETED ? : ")) 
                        try: 
                            ordertocomplete = int(ordertocomplete) 
                            inordernumber = any(ordertocomplete == i for i in ordernumber) 
                            if inordernumber == True: 
                                removeorder(ordertocomplete) 
                                integermarker = True 
                            else:
                                raise ValueError 
                        except ValueError or IndexError or TypeError: 
                                print("'"+str(ordertocomplete)+ "' IS NOT A VALID ORDER NUMBER.TRY AGAIN.")

                    if len(ordernumber)>0 : 
                            

                            print("\nORDER IS COMPLETED.")

                    else:
                          
                          print("\nALL YOUR ORDERS ARE COMPLETED.")
                          print("\n JUST WAIT 40 MINS FOR YOUR PIZZA")
                          print('\n---------------------------------------------------------------------------------')
                          
                          displayall="n"
                          a = raw_input('DO YOU WANT TO ENTER THE NEXT ORDER : ')
                          if a.lower() == 'y' or 'yes':
                               continue
                          else:
                                print'Exitting the program '
                                break

                else:
                    print("\nALL YOUR ORDERS ARE COMPLETED.")
                    print("\n JUST WAIT 40 MINS FOR YOUR PIZZA")
                    print('\n---------------------------------------------------------------------------------')
                          
                    displayall="n"
                    a = raw_input('DO YOU WANT TO ENTER THE NEXT ORDER : ')
                    if a.lower() == 'y' or 'yes':
                        continue
                    else:
                        print'Exitting the program '
                        break
    ordering=False
    a = raw_input('DO YOU WANT TO ENTER THE NEXT ORDER : ')
    if a.lower() == 'y' or 'yes':
        continue
    else:
        print'Exitting the program '
        break