So we are on the same page here,
Is it that you want to digitize paper receipts, save a copy of the receipt to storage (a hard drive for instance) and THEN be able to send the now digitized receipts to the customer through either a website or email application of some kind?
OR do you mean you just want a solution that doesn't involve paper at all. Like for instance the transaction is entered on a bank computer and then that computer just stores the receipt. The customer can then get their"digital receipt" via the Internet (web site) or through an e-mail address.
My basic misunderstanding is where you say digitize signatures and issue electronic receipts. If you are issuing electronic receipts, what is your distribrution channel (ie. HOW do you want the customer to get their electronic receipt?).
From right now, I'm think a POS solution similar to what retail outlets use is sounding like what you need.
Provide more info and I'll help you about as best I can.
-Tom