making music pause when charging stops

[Digiflame]

I recently upgraded to a DNA and mounted the gnex in my car. i got the verizon car mount for $10, got a bluetooth OBD2 scanner for torque and wired it to my stereo. the only problem i have is that when i shut the car off, the music just keeps playing (silently but it drains battery) i need a way to pause the music when charging stops, i was thinking tasker but i haven't bought or used it. i'm running cm10 and using doubletwist for music. also, i made some maps available offline but i cant search without a connection, is that just how it is with google maps?