Paper or email? That's the new question you may be asked the next time you pay for something and the clerk offers you a receipt. Is this a convenience or a hindrance to your privacy?

Paperless receipts are the wave of the future: Major banks email customers ATM slips. Mobile vendors send you e-receipts to your inbox. The number of retail stores offering customers electronic invoices is exploding. Shaleighne Murphy works for national jewelry chain Alex and Ani Jewelry.

"More customers are opting to receive their receipts via email because it's saving on paper, and it's also more convenient for them," Murphy explains.