Common sense normally dictates to you that if you don’t have enough money to buy something, you don’t buy it.
I once sold food to a chav girl who was about my age or older at the time (I was about 16 and was growing into the job). I remember her ordering a rice dish and then calling me out twice to add more things to her order. The last thing she ordered was a pancake roll and she was about 10p short, and like every good shopgirl I pointed out that I was 10p short, to which this person went: “so wha? It’s only 10p innit?”
Now I know it seems irrational to kick up a fuss over 10p so I was told to just let her off (she was giving us money and if that means that she can’t get a bus home then that’s her problem).
Although I was 16 at the time, you can’t help but think “if I let you get away with not paying the full amount now then you’re going to do it again the next time you come here.”
Had this happened in a bigger shop (let’s say McDonalds for instance) then she wouldn’t get away with it and she would pay the full amount and not give any of her attitude to the staff there. But because we’re a small business (and don’t have a team of security to escort troublemakers out) that somehow means that she can get away with not paying up the full amount or even get away with not treating us with the same respect as you probably would with someone from a bigger food outlet.