I understand that what you do is drop-shipping, right?
With our Purchase Orders PRO add-on you can create POs from orders and send them by email to your suppliers easily, but we don't have any feature like the one you mention about commissions. You are who charges the orders to your customers and specify the product prices. And what is used for the POs are the purchase prices.
You can set up them as needed, though.
And regarding the report, perhaps you could use our ATUM Export PRO add-on to export POs from a specific supplier and see the total and do any calculations in Excel.
I hope this helps.