Lol. Credit card machines? You can literally just plug in a credit card scanner to your phone in order to have a card transaction.
400 satoshi cost 1 cent of dollar currently.
EDIT: big bull I said, forgot to add the bytes
size of transaction=in * 146 + out * 33 + 10 gives 189 bytes minimum, with BTC = 2500 USD this would make a minimum of 1.89 USD. If the creditcard charges 3%, the BTC is better for payments over 63 USD.
But most local businesses are selling simple stuffs like coffee, fruits, vegetables, donuts, etc. Those stuffs don't go higher than 63$. Nice computation, by the way, but that just gives us a conclusion that bitcoin is only good to use for huge purchases. As the time goes by, the transaction fee is going higher and higher. I was surprised last night seeing that a small transaction costs 0.002BTC for transaction fee. As time goes by, that 63$ for btc being a better payment method goes higher and higher. It might be 63$ today but it can be 70$ next week, and so on.
Sure discounts attract customers. But as a local business owner, are you prepared to charge less to people just because they are using bitcoins? You're lowering your profit with this choice.