CS101 S12 - Assignment 4

due in class on Mon 26 Mar

For this assignment, you will write and test a short Python program that computes and displays a store receipt according to this set of rules:

The customer purchases exactly 3 items.
Any single item that costs over $10 is subject to a 5% sales tax.
If the total cost of the 3 items (including any taxes) is over $25, then the store offers a 10% discount.
The receipt must display the taxable and non-taxable subtotals, the tax amount, and the discount amount, if any.
Amounts on the receipt do not need to be rounded to the nearest cent, padded to two decimal places, or have decimal points aligned.

Below are some sample runs of the program. Your solution should work for these inputs, but also for others according to the rules above. User input is underlined.

Sample 1

Enter price of item 1: 9.99
Enter price of item 2: 10.99
Enter price of item 3: 12.50
RECEIPT
  Item 1  $ 9.99
 *Item 2  $ 10.99
 *Item 3  $ 12.5

Non-taxable subtotal: $ 9.99
    Taxable subtotal: $ 23.49
          Tax amount: $ 1.1745
               Total: $ 34.6545
            Discount: $ 3.46545
             YOU PAY: $ 31.18905

Sample 2

Enter price of item 1: 2.50
Enter price of item 2: 11.00
Enter price of item 3: 1.25
RECEIPT
  Item 1  $ 2.5
 *Item 2  $ 11.0
  Item 3  $ 1.25

Non-taxable subtotal: $ 3.75
    Taxable subtotal: $ 11.0
          Tax amount: $ 0.55
               Total: $ 15.3

Sample 3

Enter price of item 1: 9.99
Enter price of item 2: 8.99
Enter price of item 3: 7.99
RECEIPT
  Item 1  $ 9.99
  Item 2  $ 8.99
  Item 3  $ 7.99

Non-taxable subtotal: $ 26.97
    Taxable subtotal: $ 0.0
          Tax amount: $ 0.0
               Total: $ 26.97
            Discount: $ 2.697
             YOU PAY: $ 24.273

Notes and hints

Start with the simplest pieces of the functionality you can, and get them to work before adding more. For example, just ask for the price of one item, and determine whether or not it is taxable. Run and test that program before moving on.
We need the user to input numbers with decimals, which are called ‘floats’ in most programming languages. Recall the syntax of the input statement. The prompt is inside the quotes. The variable price1 will then contain whatever number the user typed.
```
price1 = float(raw_input("Enter price of item 1: "))
```
The problem description refers to percentages, such as a 5% tax rate, and a 10% discount. You cannot use the percent sign directly in Python, instead we have to divide by 100 and use that decimal number. So 5% is written as 0.05, as in:
```
tax = taxable_sum * 0.05
```
Try to use sensible variable names, such as tax, total, discount, etc. Names cannot have spaces in them – instead we use the ‘underscore’ character, as in nontax_sum.
Your program will use several conditional statements. The syntax is shown by example below. Don’t forget the colon at the end of the if line, and use indentation (tab key) to show which statements are controlled by the condition:
```
if price1 > 10:
    taxable_sum = taxable_sum + price1
else:
    print "  Item 1  $", price1
```