You are charged a percentage of a cc transaction, and an inquiry fee each and every time you process a credit crd. While the inquiry fee is typically very low, somewhere between 22 and 36 cents, the real cost is in the percentage of the total amount being charged. This is known as the Credit Card Rate, and depends upon the type of transaction and crd being processed.
Credit crd rates depend on the kind of credit crd being used, how it is processed, and the duration it takes the merchant to batch the transactions for processing.