On a clean installation of Moodle 2, I created course with a Folder and added 3 files totaling 168 MB to it. I then deleted the Folder from the course. I measured the size of my data folder and took a screenshot of the files table in my database at 3 points:
1. After uploading the files
2. Immediately after deleting the files
3. After the cron job ran at least once
At all 3 points, my data folder was 170 MB. The labeled screenshots of the files table are attached.
I still have the test installation and can provide access to it if necessary.