Get one of those large notebooks, and store all receipts in it. Sort it by store. Also, enter each invoice on an excell spread sheet (date, invoice #, job name, price and general description of materials). It's really not all that hard. Believe me, I know where you are coming from.
Get a separate notebook for Govt agencies, insurance, ...etc. If you get in the habit of filing all papers as soon as you get them, you will be suprised at how much smoother things can go.
Just saying, Excell can really be a great tool. Once you get familiar with the basics. It's really not all that hard.