Get an Evernote account (free) at www.evernote.com
Scan in your receipts as PDF files (this will make them searchable).
Create "notebooks" in Evernote and use that to organize the receipts
In addition to this, when you create a Evernote "note", you can add multiple custom "tags" which gives you a second dimension for
organization and searching.
So, say you have all the receipts for your jobs, and you create a new folder for each job. Load the receipts in there, and then say, on a receipt you add a tag for "hardware" and one for "Home Depot".
Later, you can say "show me all receipts for "Home Depot", or all receipts for "hardware". Of course, if you just select a project folder, you'll everything related to that.
YOu could also do the reverse. Folders based on say "hardware", "wood", and tags like "John's Kitchen"
Evernote is "cloud" based, so you can see your content from any browser anywhere, or even from a mobile device such as an iPhone or iPad.
There is also a thick client for your computer so you don't have to use the browser.
It's free as long as you stay under the certain limit of notes per month.