Item Costing, Layer Cost for FIFO

Hello,

I am implementing on a client site that uses FIFO costing method, the scenario is they import some inventory items which goes thus

PO is raised with the item, quantity and price.

When the item arrives, it comes with some charges such as import duty, clearing cost, shipping charges etc

The issue is the user wants to be able to capture these additional charges on the system in order to arrive at the item unit cost before bringing in the item into the inventory.

Please , I will like to know how best i can do this on the system.