Price Margin

I was wondering if there was the ability to at cost to products in addition to the selling price to calculate the margin or profitability of a product?

-- HikaShop version -- : 2.2.3
-- Joomla version -- : 2.5.17
-- PHP version -- : 5.3.24
-- Browser(s) name and version -- : Firefox 27.0.1

If you want to enter the cost of products, it's easy. Create a custom product field via the menu Display>Custom fields and you'll be able to enter your cost in it.
But then, what is the purpose for that ? If you know the cost and the price, you already know the margin...So there is no need for HikaShop to calculate it.