The Cash Register class should allow you to pass an amount to the cash register, calculate your total, collect a payment and then return the balance after running through the program.
- There is a purchase method that takes a floating number and adds that to the total.
- There is a total method that returns how much is owed.
- There is a pay method that takes one floating number for how much is paid. It should return how much change is given.
- When the Cash Register is initialized is should begin with a starting balance of 0.