Sales are easy: the till adds them up. Cost is the hard part. Meat is bought by the kilo and sold by the gram, a large burger uses more than a small one, every extra cheese leaves the shelf without anyone writing it down, and food cooked for an order that was then cancelled goes in the bin. So at month end the profit is lower than expected and nobody can say why.
In Loqma, stock is wired to the till and the menu: every item has a recipe, every sale takes its ingredients off automatically, and every delivery updates the cost. So the number you see is the one on the shelf, and the gap between them has a name and a reason.