Is there a secret technique I'm unaware of? No matter what I try I lose. I even found an exploit and it was still unwinnable. (speaking of that exploit, If you're close but the timer keeps getting you, keep shaking the jar, the timer resets giving you infinite time.)
Try this: When you first start, arrange them in order of size. Tiny reds go to the far left edge, then pink, purple, yellow, rainbow, etc.
If you don't have the space, drop em as close as you can to where they should go. If you're paying attention, you should be able to get the first swirly candy at minimum before it becomes difficult to prevent the candies from stacking up.
Keep candies of similar size together, but don't cut them off. Don't cover a yellow with a purple, but drop it close. Try to keep dumping the smallest two sizes at one edge; the little reds especially can pretty reliably fall down to the bottom if you shake a couple times.
Lots of little stuff like that.