I decided to add Boolean variable to this code of solving it and whenever I ran my code I get additional 1ドル added if the total shipping order exceeds or equals 50ドル. Why?
This is the code:

Program to calculate a shipping order and give a tip of free shipping if order exceeds 50ドル else 10ドル fee

shippingFee = False
sumTotal = 0

orderTotal = float(input("Enter the total amount of order "))
if orderTotal >= 50:
shippingFee = True
print("Shipping is free")

else:
shippingFee = 10
print("Shipping fee will cost additional 10ドル")

sumTotal = orderTotal + shippingFee

print("Your total shipping fee with order is $%2f" % sumTotal)
print("Your total shipping fee with order is $" + str(sumTotal))