Shipping costs: Real cost of shipping on financial reports

Hey guys!

As you know, some businesses (or the major part) don't charge the real cost of shipping to their customers.
Some charge a flat rate, some charge a lower value, others practice free shipping.

I was wondering if anyone had the same issue as I did regarding the financial reports.
We can have the "costs of goods sold", but there is no option to have the "costs of shipping".

Imagine this:
I have a shipping rate for Europe, which costs me 15€ but I only charge 8€ (the brand covers the 7€ gap).
There should be a place to insert the "cost of shipping" on the shipping rates as we have on our products.

If there was any way to add this value to the financial reports we would be much more aware of the numbers of our business.

Is there any app that does it?

Let me know your thoughts