Production - How to add a fixed % of cost on the Overall cost

Hi,

I need to add a Fixed % of cost on the total cost of the Finished Product.before ENDING the Production

e.g Material cost 100

Labour 20

OH 10

TOTAL COST 130

I need to add 10% (fixed always) of the Total Cost which is 13, so that when I END my Production order the Finished product has a Total cost of 143. I did not find the setup for this.

Regards

Thomas Philipose