As serpyre suggested, you can do it in Excel or Google Spreadsheets, however, I wouldn’t recommend it. It is true that there are many small businesses that use nothing but Excel, but it is also true that nearly all of those companies at some point will have a catastrophic data loss/corruption due to their reliance on storing data in a spreadsheet.
Spreadsheets are designed for performing What If Analysis and are excellent tools for manipulating data, and that is exactly why they do not make for a good data storage application. Your data’s integrity will be at constant risk if you use a spreadsheet application for data storage.
For the most part, any accounting application that you can integrate with your web store will work for your purposes. You already need to do accounting, why not use tools that are designed for this exact purpose?