>>7
I didn't see this one, but all I can guess is confidence and sleight of hand.
It's rude to count through a lot of notes, in more upmarket stores you expect to be trusted, and if you show the right attitude you're likely to be. A shop that sells expensive rings expects people to rush in with guns if they're gonna steal anything.
And it's fairly easy to switch a wad of notes with a wad of paper, such that you could count out the notes in front of people, and simply make a switch when you hand them over.
A little NLP to keep people in a slightly confused state where they're less likely to notice something's up and you're laughing.