Who sings the JCPenney commercial song?

Assuming the commercial you're referring to is the one where people are doing all the magic tricks -- the lady pulls a crutch from a little purse, the phone booth fills with water and collapses, the girl climbs out of the filing cabinet in the office -- then it's "Music Box" by Regina Spektor.

"Life inside the music box ain't easy / the mallets and the gears are always turning / and everyone inside the mechanism is yearning to get out / and sing a different melody completely / so different from the one they're always singing / and everyone inside the mechanism is yearning to get out..." Watch the video here: YouTube.com/watch?v=-aH0qfU6bo8">http://www.YouTube.com/watch?v=-aH0qfU6bo8

(Ingrid Michaelson's "The Way I Am" was, I think, used in an Old Navy commercial. Ah, the things one learns from TV... http://www.YouTube.com/watch?v=v-7luX488iY )