You’ll notice if you do a Disk Clean-Up or run a program like CCleaner, *.tmp files will be removed.
*.tmp files are temporary files. Dump5515.tmp sounds like a standard log. When programs run they have memory leaks, extra little processes and interrupts, and it all gets logged. Well, eventually that bogs down the program and is dumped…when that happens, we get dump files. If you are uncomfortable removing these files yourself, there are several free applications that do so. I suggest: CCleaner.