Walk All Over Me (movie, 2007)

Alberta, a mousy young woman with the survival skills of a snail, loses cash that isn't hers, so she runs from her small town to Seattle where her old babysitter, Celene, lives - a dominatrix with a classy apartment and a life plan. She lets Alberta stay. Alberta gets a job as a checker at a supermarket and becomes fascinated with Celene's work.