My Daughter Is A Thief! How Do We Fix This?

We're finding out that our five-year-old daughter is a dirty lil thief... or at least that is the phase she is in.  She'll take things from school, Wal-mart, Target, etc.  We've tried to warn her how bad stealing is, that it is wrong, "you can go to jail", etc.   Like I said, it's probably a phase, but it needs to stop.  How did you fix the issue/phase of your child stealing things?