We had to pay the parking fee for the week ($70) upon arrival at the terminal last week. They take cash or credit cards.
We used cash to pay for parking, put some down on our account so we wouldn't end up with a gigantic credit card bill at the end of the week and also used cash for room service tips, porter tips on both the day we checked in and the day we checked out, and finally, we used cash in the ports as much as possible when we were shopping.
We also added cash to our room steward's tip envelope, along with the tip voucher on the last night, because he was just so terrific!