3yr old sucking fingers still...?

So, does anyone have any suggestions on helping stop my 3yr old from sucking her fingers. She never took to a pacifier and she doesnt suck her thumb, it's her two middle fingers. And it's quite annoying too. I can't seem to get her to stop... hot sauce doesnt work (she sucks it right off), painting her nails doesnt help (she waits for paint to dry), and pepper doesnt help. I'm really skeptical on trying the stuff they sell over the counter... any hints?