A teller is either someone who tells some sort of story or a person who works in a bank. A bank clerk who loves to talk about her adventures? She's both kinds of teller.
You might be a teller of tales, known for spinning stories, or a teller of lies, famous for your fibs. If you're a teller at a bank, you cash customers' checks and make their deposits. There aren't as many bank tellers as there once were, since this job is increasingly done by ATMs, or automatic teller machines. Teller comes from an obscure sense of the verb tell, "count."