collecting sales data

First thanks for the help. Here is my question.

At the time of sale, I input data for each sale as follows, simplied version:
A1 = Receipt number
A2 = Buyer name
A3= Total
A4= Date

I need to collect cerain sale's data within the spreadsheet, build a
database of sales. I can prenumber the receipts in the database and use an IF
statement with a circular reference (iterations) based on the receipt number.
However, if I mess up on my input sequence (forget to advance the receipt
number for new entry), I mess up the previous sales entry.

Just wondering if there is a simplier or safer way of doing this. Thanks
again, Tom