I will say, one time a few years back I needed to get a receipt from a purchase more than 60 days old. I called the local store, and she said "just give me your credit card number and I can lookup your transactions". With just my card number she was able to see every transaction I made with that card (and find my purchase I needed the receipt for). So (at least 3-4 years ago) it was being stored somewhere searchable by people in the back office.