An ordinary and unique coffee shop

Less than a five-minute walk from the East Railway Station in Munich, Germany, there is a restaurant called Cafe Liebling that looks ordinary, with its mini space stuffed with lovely pendants and gadgets. Ordinary as it is, it has a unique business philosophy that allows all customers to decide how much they spend, from simple coffee, lattes and cakes to a set of breakfasts. There is no cash register in the store, only a small glass jar. Let you order something and throw it in. If you go in and order a cup of cabbage, how much will you pay?