That too is sort of a business needs driven application. It doesn't occur to someone without sales or maybe accounting domain knowledge that prices on a 'cut'

That too is sort of a business needs driven application. It doesn't occur to someone without sales or maybe accounting domain knowledge that prices on a 'cut' order, bill, or other receipt, while numeric in nature, must be fixed and distinct to that order/line item when it's finalized. It becomes no longer a number representing what a given thing should cost in the future, it is now part of a record reflecting the contents of a legally binding contract.