Sets a paid order's tip after payment; zero removes it. tipCents is the order's whole tip: the difference is posted as signed tip rows shared over the tenders not wholly refunded that were tipped — a cut in proportion to their tips now, never taking one below zero; a raise in proportion to what each was tipped — so lowering and restoring a tip puts each tender back where it was. What no such tender can take lands on the latest tender not wholly refunded. The response names the tender the change was posted on, the newest when it is shared over several. Refused with BAD_REQUEST tipWindowClosed once the order's shift has closed or for an order with no shift, tipsOff where the venue's POS tips are off, orderCancelled for a cancelled order, orderNotPaid before the order is fully paid, noStandingPayment when every tender was refunded, and qrTipped for an order a guest tipped through the QR menu, since that tip rode their MyFatoorah charge. Changing a tip already set, or any tip on a done order, needs order:adjustTip.