Costing Relevancy to be activated

Dear Experts

As per our costing requirment,they want to valuate materials based on certain parameter like count in Textile industry,

suppose we are putting 100rs.mtr &

if we are using 60s count yarn price should pick 25%

if we are using 80s count yarn price should pick 50%

For this activity to be done,We want costing relevancy in BOM & Routing to be activated by percentages.

But option is not working in our client,shall we have do any customisation for that.

Regards

Sandeep