Sometimes with Jailbreak the other value will get messed up and there is only two ways to remedy it.
1. While the device is plugged in press and hold the home button and then the sleep/wake to do a hard reboot. Re-sync and sometimes it resets the value.
2. Uncheck something that has a high value like a music playlist or film. Then re/check and re-sync. Each time I've used these methods it's successfully reset the value.
You can clean out your mail, messages as well which will count as other. You can also try this directory which hasn't been mentioned.
Var/Cache/Apt/Archive/Partial
These are failed downloads which can accumulate and they can all be deleted from this folder.