Is it possible to add the purchase price in this plugin ?

Hello,

Is it possible to add the purchase price in this plugin ?

For exemple :

I buy to my supplier a tee shirt red : cost 10€/pc
transport cost : 5€/pc
cost of good = 15€
purchase price = 10€

This difference of 5€ take problem when i make an inventory ( $ amount in stock ).
The value of stock is false is i add the transport cost. ( value which I declare for pay taxes to the state )

The calcul on profit margin ; profit stay the same ( = cost of good)
Only the amount of inventory must be different.