As a business owner, I'm really interested in Return on Investment. That is the amount of cash that I outlay and the return I get from that money.
Here's the thing, If Amazon take out fees out of the sales amount, I don't want to include those costs in the ROI. I want the net profit divided by the landed cost, or Cost Of Goods.
Most dashboards are using net profit/cost of goods but there are a few taking net profit/total cost.
You can consider cost of goods as the amount you need to replace a sold unit, including manufacture, sea freight, taxes and charges to get it in a warehouse ready to sell.