Landed Cost in an average costing organization

Hi,

My requirement is for an average costed organization ABC in USA, if Supplier 123(say based in Japan) ships item A, then the landed cost % should be 20% whereas if Supplier 456(say based in USA), ships to organization ABC, then the landed cost % should be 10% etc. This is because the freight, handling charges for bringing an item from a Japanese supplier will obviously be more than the charges incurred for shipping them from a local US supplier.

Hence the question is what is the standard (or custom) solution of handling the above requirement?(Requirement: Ability to define separate landed cost % for a Warehouse-Supplier combination?)