All three charge on the same base
Each marketplace defines its fee base as the total the buyer pays. Amazon puts it as “An item’s total price includes its list price, as well as shipping costs and any gift-wrapping charges.” Walmart’s table says “Total sales price includes item price as well as shipping and handling, gift wrap and other charges.” eBay charges on the total amount of the sale, shipping included. So the item price and the shipping you collect go in together, and that one number is the base for all three columns.