I usually use my credit card and I haven’t noticed any extra charges, I know some places are adding on things like employee health insurance charges but I haven’t seen it yet.
Credit. I only occasionally use cash and I don't use my debit card for anything other than ATM transactions. I've never noticed a different charge.
There is a local food truck that I usually pay cash at. And I always used to pay with a check at the vet because I heard the old vet complaining about the fees, but since the new vet took over, the young receptionists seem confused by checks so sometimes I pay by card.
A small business owner told me that it all comes out about even. Cards have processing fees, but cash is sometimes counterfeit, can get lost, and is a pain to handle (you have to lock it up or take it to the bank every night, etc.), and checks often bounce, which racks up even larger fees.
The last time I seen someone use a check it was ran like a card. This was at a large store not a small business. They ran it through something, it cleared there and they handed the check back to the person.