Here's how Square Enix's Online Back to School Sale works: the first game is 20 percent off, adding a second takes it to 30 percent off, going all the way up to 50 percent off for three or more games. So, if I'm reading this right, you can buy as many games as you'd like from the available titles for half price.
Note that this is only on select titles, but includes some new games like Lightning Returns: Final Fantasy XIII, Murdered: Soul Suspect, Drakengard 3, and Final Fantasy X/X-2 HD Remaster. I love how Chrono Cross is always on sale like it isn't one of the greatest JRPGs ever made.
Check out the online store for the full list of available titles.