Yes... you can make cash payments on your sign and sail account whenever you want. Just go to the purser desk... have them scan your card and it will bring an up to date balance charged to your account, and then cash it out. Only drawback is on last day (especially in evening) many people are using the information desk to get change (for tipping) or have lots of questions about disembarkation the following morning so you usually will stand in line for a while.