Let's keep it simple.
1) Snap a photo of your receipt
2) Add some simple details
3) Export your receipts as a PDF via email
All of your receipts will be backed up to your iCloud account. This means that if you lose your phone or delete the App, your saved receipts will be restored the next time you install the App. Further, your saved receipts will be available on all of your iOS devices, simultaneously.
You can export your receipts within a certain date range, by selecting a 'from' and 'to' date, in the library viewer.
- iPod Touch