Purge is a new Cydia tweak that allows you to close all of your backgrounded apps at once. To do that, install Purge, double tap on the home button to bring up the multitasking cards, tap and hold on any card and a pop-up will show to ask you if you want to close all of your opened apps. Tap on yes and you’re done.
FSM EXCLUSIVE DEAL Purge is available for free in Cydia via BigBoss repo.