I love the episode when Granville strikes a bargain with Arkwright about getting a new till when he states in exchange he will get Arkwright access to Nurse Gladys's bedroom. It is peppered with the phrase "How Much!!" when the salesman obviously quotes too high a price and sadly the new till does not arrive , which of course it never would given the comic interlude the till provides in every show.
I have also noticed that Arkwright just pushes random keys and the amount rung up never matches what he says is the charge to the customer nor does the money he deposits and occasionally removes match the cost and change due , it is clearly just the comic effect of the till that was the aim.