Accounts 2 Checkbook (by SVT software) has the capability to take a picture of a receipt when adding a transaction. I use this app on my iPhone 6 to balance my checkbook.
Scanbot (by doo GmbH) is a scanner and QR reader that can be used to scan documents and receipts. I use this app on my iPhone and iPad to save documents.
I'm sure there are others, try searching for document scanner in the App Store.