How can I force a media rescan on Lollipop? I would like to force a rescan so that the MTP file listing is correct when I use Android File Transfer on my Mac.

I've tried a half dozen apps but none of them seem to work on Android 5.0.

I have rooted my device.
You can try heading over to the Settings>Apps>All, Look out for Gallery app, tap over it and Clear Data and the Cache Stored.