Within Microsoft Dynamics GP, go to the customer card and go to the Additional button at the top of the menu and select the Payment option. You have the ability to store multiple credit card profiles against more than one merchant account.
The most important piece of information to populate after the credit card information is the zip code and street address that is associated with the credit card. Having the correct zip code will result in a downgrade in the interchange fees charged by the card associations.
The profile can be used on future cash receipts and sales order transactions in GP.