Manufactured Items - Country of origin

Has anyone done a calculation for the country of origin for manufactured parts? Blowing down the full BOM (past sub-assemblies) and gone to the point of the purchased parts and calculate the country and % content.

I heard a rumor there is a method in costing that will blow all the way through a BOM to the purchased part that can be used to help me out with the issue. Does anyone know what that may be?