AlwaysClose helps you quickly close applications open in the background, it is compatible with iOS 6

  AlwaysClose is a tweak launched a few months ago Cydia, and the one that allows iDevice owners to more quickly close applications open in the background. To close an application open in the background, you have to long press the application icon until it starts to "shake" and the close button appears, press it and the application disappears. AlwaysClose simplifies the process because it permanently displays the close button next to all open applications in the background and you will immediately close everything you don't need.

  AlwasyClose is not the first or the last tweak that offers this functionality, but it is free and you can install it right now from Cydia.