Credit/Debit card transactions have a 2.99% processing fee for the initial transaction.
ACH transactions have a 0.89% processing fee for the initial transaction.
Those fees can be stopped if you void the transaction, but once they are processed the fees will apply.
All refunds have a $0.25 per transaction fee and that is the only fee that applies.
ACH Returns have a $5.00 fee
Chargebacks have a $15.00 fee.