I have lumia 710 with OS Version 7.10.8862.144 and firmware revision number - 1600.3036.8853.12440 When I use Storage Cleaner, it shows 15.48 MB available space and temporary files - 5.28 GB. I deleted the temporary files using the Storage Cleaner and then reran the Cleaner. It was the same status again. Can a phone have such big size of temporary files. When I check with Zune, it shows about 4.5 GB available space.
As mentioned in my comment, Storage Cleaner is a 3rd party app which has no proper method of clearing the temporary files. It uses a kind of hack (ie. fills up your phone with data) until it's full to try and force the phone to free up more resources by deleting its temporary files.
This will not always work, and some of the temporary files are stored for performance reasons, such as old emails, messages, map data, etc.
The Zune software, as it's official, will list the correct amount of free space so I would stick with its figure and ignore any 3rd party app's gimmicks.