In short, no.
Disk cleanup will not know what other programs will need cleanup. The story is simple. There is no published procedure or "API" to registrer your new software that you write with Microsoft's Disk Cleanup.
The Compress Old Files does NOT delete them. It merely uses NTFS on-the-fly decompression to store them in less space.
As to "safely" deleting things, the words seem to be an oxymoron. A file that is deleted is gone and therefore it is very unsafe for the file you are deleting.
If you meant what havoc you can cause to some application, that's different. For that, the adage is as follows.
"We only lose what we didn't backup."
XP Pro 2002 service pack 1
CPU 2.53 GHz
Was under the impression when one used disk cleanup that all the files would be completely cleaned out. My webclient/publisher temporary files and compressed files are never cleaned to zero (0). There are always files left there. Anyway to clean these out since the directions say they can be safely deleted ?