I used OpenERP 8  -  Install POS Module  with  Multiply Company

I need to add Button (Link to other website) In POS.Customer Screen

And I will send Get String too.

CardID=<Customer.Name>

TranID=<pos.order>

Total=<pos.order.totalAmount>

Send Like This : www.xxx.com/MemberShip/Check.php?CardID=<Customer.Name>&TranID=<pos.order>&Total=<pos.order.totalAmount>

Capture Image : http://i57.tinypic.com/2uz9pqr.jpg