-num is total price
-price is self explanatory
-lowest is used to store the lowest number
-HST is the tax
-items is the total amount of items

num=0
price=0
lowest=0
HST=0.13
items=0

print "Enter 0 to print receipt.\n-----------------------"

while price>0:

price=raw_input("Enter your price here: $")
price=float(price)
num=num+price#num is the subtotal
print "tag2"

while price<0:
print "Invalid number"
price=raw_input("Enter your price here $")
price=float(price)
num=price+num
print "tag 3"

if (price>0):
if (lowest<=price):
lowest=price
print "tag6"

items=items+1 #total amount of items

print "Subtotal: " ,num
print "Discount: " ,lowest
print "After discount: " ,num-lowest
print "HST: " ,(num-lowest)*HST
print "Total: " ,(num-lowest)+((num-lowest)*HST)
print "-----------------------"
print "tag4"