D'oh! I just realized what forum you were in (jail breaking)....
No, there is no tweak to kill an app you're in (that's the Home button's job). And, I think the terminology is confusing. The AppQuit description talks about currently running apps - but those are the apps that are in the multitask bar, not the one you are actively using. There are a number of tweaks to remove apps from the multitasker: RemoveBackground and WeekillBackground come first to my mind. Then, there are some toggles for the Notification Center, plus some that can be loaded on the Springboard.
If I may suggest - have a Google for remove background tweaks. There are a lot.
Hope this helps.
Marilyn