A second suggestion from my old bottle shop days: Have a friend come in and pretend not to know you. They pick up something cheap plus a bunch of expensive spirits. You scan them with the little handheld scanner thingy but just scan slightly to the side so you miss the barcode on the expensive spirits. They pay by card so there's no video evidence of the wrong amount of money changing hands or anything dodgy. These days you'd probably also have to be aware of whether there's a payment threshold for PIN numbers being required or whatever that would be a giveaway on video, but I'm sure you could get around that.

I saw way too many idiots get caught with their hand in the till, which is the absolute dumbest way to steal from your work