I want to incorporate the 'Vendor/Supplier Rebates' process in OpenERP but have not seen anything that comes out of the box for handling this. Can someone point me in the right direction?

Further Clarification: Vendor/Supplier rebates are used when a supplier offers a renegotiated price on products to the customer (or retailer) which increases the margins of the retailer and encourages them to pass on these rebates to the end customer. For eg. Retailer (ACME Corp.) bought 100 laptops for $ 600 each from Supplier (Bell Corp.). Now, 3 weeks after these laptops were delivered to ACME Corp. the supplier revised the prices of these specific laptops to $540. This rebate of 10% is now available to ACME corp. to pass on to the end customer. Rebates offered are of various kinds (the above is just one example) and a practice that is very prevalent in the retail industry.