Mini project: a shop receipt

Time to put the whole track together. You'll build the till program for Date Palm Grocery, a small neighbourhood shop. The cashier types the customer's name, two items with their quantities and prices, and the amount the customer pays. The program prints a complete receipt with VAT and change.

You won't write it all at once. Professional programmers build larger programs in milestones: small steps that each leave a working, tested program. If something breaks, the problem must be in the step you added last. Each milestone below starts from the solution to the previous one.

The finished receipt

For a customer named Lina who buys 2 bags of Rice 5kg at 32.50 SAR and 1 Dates box at 24 SAR, and pays 110 SAR, the finished program prints:

================================
DATE PALM GROCERY
Customer: Lina
================================
Rice 5kg x 2 @ 32.50 = 65.00
Dates box x 1 @ 24.00 = 24.00
--------------------------------
Subtotal: 89.00
VAT 15%: 13.35
Total: 102.35 SAR
Paid: 110.00 SAR
Change: 7.65 SAR
Thank you, Lina!

Both divider lines are 32 characters long.

The plan

Following Writing small programs, first decide what goes in, what comes out, and how to get from one to the other.

Inputs, in this order: customer name (text); item 1 name (text), quantity (whole number), unit price (decimal); the same three for item 2; amount paid (decimal).

Calculations:

• line total = quantity × unit price, for each item
• subtotal = line total 1 + line total 2
• VAT = subtotal × 0.15
• total = subtotal + VAT
• change = amount paid − total

Output: the receipt above, with every money value shown with two decimals (:.2f).

Hand check: 2 × 32.50 = 65.00; 65.00 + 24.00 = 89.00; 15% of 89.00 is 13.35; total 102.35; change from 110 is 7.65. These are the numbers your program must produce.

The trickiest line

The item lines pack four values into one formatted line. Here is that line on its own, with fixed values, so you can experiment with it before you need it:

item = "Rice 5kg"
qty = 2
price = 32.5
line_total = qty * price
print(f"{item} x {qty} @ {price:.2f} = {line_total:.2f}")

Notice that qty is shown without :.2f (it's a count, so 2, not 2.00), while both money values use :.2f.

Your program reads the values with input() instead. The checker types the inputs in the order listed in the plan, and only compares what your program prints, so you can word your prompts however you like.

================================
DATE PALM GROCERY
Customer: Lina
================================

================================
DATE PALM GROCERY
Customer: Lina
================================
Rice 5kg x 2 @ 32.50 = 65.00

================================
DATE PALM GROCERY
Customer: Lina
================================
Rice 5kg x 2 @ 32.50 = 65.00
Dates box x 1 @ 24.00 = 24.00
--------------------------------
Subtotal: 89.00

VAT 15%: 13.35
Total: 102.35 SAR

Paid: 110.00 SAR
Change: 7.65 SAR
Thank you, Lina!