Are you maximizing your profits on Whatnot?

Lately, I've been diving deep into my selling stats on Whatnot, and it's clear there's a lot to consider beyond just the sale price. With all the fees, shipping, and miscellaneous costs, I sometimes wonder how other sellers manage to keep track of their actual profits. How do you ensure you're not selling at a loss? Do you use any tools or methods to calculate your break-even point before going live? I'd love to hear your strategies or any tips for keeping everything in check, especially if you're selling across multiple marketplaces.