Gross revenue is what customers were actually charged: the ticket price of everything ordered, less price reductions and discount codes, plus the shipping they paid, with VAT still inside. It is the top of a statement once discounting has been accounted for, and the figure returns and tax are then taken out of.
The distinction that matters is between what was asked and what was charged. The ticket value of everything ordered is one number; gross revenue is that number after the price was reduced and the code was applied, which is why two stores with identical catalogues and different discount habits report very different gross revenue on the same volume.
Shipping charged to the customer belongs in it, because it is money the customer handed over. The cost of actually shipping is a separate line further down, and the two are rarely equal: most stores under-recover delivery, and that gap only becomes visible when both halves sit on the same statement.
It still contains VAT, so no margin can be computed on it. Working from gross revenue down to net revenue is the bridge every cost percentage depends on, and doing it in the wrong order, tax before refunds, overstates both what you kept and what you owe.
