If you want an easy way to keep your records for the ATO consider an online accounting service such as Xero. It takes me about 10 minutes a week to do my bookkeeping and the amount of time it saves me is well worth the money it costs (which is a tax deduction as well). I have the ebay side of the business, a website and a retail outlet so it is a reasonable size business.

Come tax time or BAS time (for those who are registered for GST) it only takes a few minutes to generate the reports you need for the ATO  or your accountant.