It's a limit imposed by the franchises for credit card transactions. For some time I was a network engineer for one of the majors US retail division. Here's how it works: let's says it's a Valero station. Velero doesn't actually own the station, it's a franchise but they do process the credit card transaction. In the case of Valero, they (Velero) are responsible for the first $74 of any credit card transaction. The franchise is responsible for any amount higher. Most franchises will cut off at the majors limit. If for any reason the cc transaction is later declined, the franchise doesn't lose money. This could be a case say if the sat link to the major is down and cc transactions can't be validated, the local POS will authorize the transaction, up to cut off amount.