Which Credit Card Terminal/Company for POS2009?

I am just about to setup an MS Dynamics POS 2009 solution for a customer. Where I am stuck at is the customer wants to use an independent hardware solution for capturing Credit/Debit payments using a terminal which picks the total amount from POS2009. I have searched high and low and cant figure out which one is compatible with POS2009. For example like the ones you find in Vons, Albertsons, Ralphs. Any help is much appreciated. This is in California, US.