People point this out a lot, and it is very true, and merchants love to whine about it, but they never point out the costs of handling cash.
You have to count it into the till, make change, balance the till, count and recount your deposit, and then haul it to the bank to deposit and pick up your change order, or pay an armored car service to do it for you. And hope nobody robs you in the meantime, or slips you a bogus $50.
For cards, big stores don't even need to print slips for their records, it is all in the system. For small stores you can just staple the slips together by type and drop them in a box in case someone gets a stick up their butt and decides to audit you.