You are, of course, assuming that the OP is JB.......even though this isn't in the Hacking Section?
To the best of my knowledge there is no way to close all apps with a stock iPad, without closing them one at a time in the task bar.......although I'd love to be proved wrong.
Unfortunately, The Archangel, you are correct: there is no way to do this on a stock iPad. And, yes, there is a way with a jail broken iPad. But, again, that is only with a jail broken iPad.