Label Markup
Markup applied to seller self-serve shipping label purchases (POST /shipping/self/quote) — sellers never see the underlying carrier cost.
Markup formula
finalPrice = max(carrierCost × (1 + markup% / 100), carrierCost + minimum fee)
e.g. 15 = +15% over the carrier's real cost.
Floor markup — applied instead of the % when it would be higher (protects thin margins on cheap labels).