I've been trying desperately to reconcile 'tally' with 'tell', for want of a better explanation but the connection, unfortunately, seems too obscure. Incidentally, the Tally-man is still a title used for someone who collects the premium against high-interest cash loans or instalment payments OR a man who lives with a woman outside of wedlock. I'm still looking (for the origin of "to tell off", not for a woman outside of wedlock).
Tell (someone) where to get off, to express anger at, rebuke strongly, 1902. Tell off, 1919.
Tell on, to inform on, 1900.
From "Listening to America" by Stuart Berg Flexner (Simon and Schuster, New York, 1982).
Oh I agree with you that a 'teller' is someone who 'counts' in whatever context, a teller in America is a bank counter clerk, a money counter but are you suggesting that someone who "tells" another off is counting from a theoretical list of wrong-doings?
Here's a first! We disagree. Smokey Stover, the writer of the final paragraph in the link, seems to be referring to British military jargon to explain an AE slang term.