Disk space still being used after clearing cookies and site data, history, and nothing shows in manage data. Why is disk space still being used?

This is what it shows: Your stored cookies, site data and cache are currently using 5.5 MB of disk space. After I click the clear button. The 5.5MB is under the cached content. There is nothing under the manage data tab. I've cleared the history and nothing shows there. Should there be 5.5MB disk space being used after I click the clear data tab? If not, why doesn't it clear?