help needed for intro while loops

I need help coding this project using while loops and cout/cin.. It is suppose to be one while loop for the whole thing and inside of the first while loop is the second while loop for each sale separately. I cannot figure out how to start that?

** completely new at programming and this is a project that is due soon for class


You have been asked to write a program to calculate sales totals for a general store. Your program will not know how many products each customer will buy, so your program will have to repeat the process until the last product has been entered (use -1 for Product ID to end each sale). After each sale your program must ask if you want to do another sale (Y –continue, N – end program).
At the beginning of the day, the cash drawer has $500 in it. At the end of the program you must display how much money is in the drawer after handling all your sales transactions.
Input
Your program must take the following input:
• Product ID Number (int)
• Quantity for each item purchased (int)
• Cash Received at the end of the sale
Use the following dataset to determine the price and taxability for each item.
First Sale:
Product ID Price Quantity Taxable
101 $65.00 2 Yes
102 $12.50 1 No
103 $24.50 5 No
104 $38.75 4 Yes
105 $17.80 6 Yes
106 $16.50 2 No
107 $42.85 8 Yes
108 $32.99 2 Yes
109 $28.75 1 Yes
110 $51.55 1 No

Second Sale:
Product ID Price Quantity Taxable
102 $12.50 1 No
103 $24.50 1 No
106 $16.50 1 No
107 $42.85 1 Yes
108 $32.99 1 Yes
109 $28.75 1 Yes

Third Sale:
Product ID Price Quantity Taxable
106 $16.50 4 No
107 $42.85 3 Yes
108 $32.99 1 Yes
109 $28.75 5 Yes
110 $51.55 2 No

Calculating Tax
For those items that are taxable, assume a 7.5% sales tax. Be sure to keep a running total of tax for the each sale.

Getting Started
You must use the starter file provided with this assignment.
What to turn in:
• A copy of your source code
• A printout of your program’s output

What does the starter file look like?

As this is for homework for a course, we won't write the code for you. Have a read of http://www.codeguru.com/forum/showthread.php?t=366302

We'll try to assist if you have a specific question regarding code you have already produced - or point you in the right direction as to how something might be done. But just giving a program spec and asking for help to code it is a non-starter. Many members of this forum would call that cheating. You are being tested on what you know, not what I know.

Have you produced a program design from the spec? If you haven't I suggest you do before you even write one line of code.