Several people have commented on the idea of getting a gadget to "round corners" on tiles. Memory Keepers is an online store for things like this and they have one on sale (from $25 to $22.49) right now. click here. They call them "Corner Chompers". One really nice thing the more expensive one does is allow you to choose between two sizes of "chomp" where the one above only is one size. And the more expensive one allows you to cut through plastic and acrylic so I am thinking it might allow you to do more than one paper at a time. You will also see a video of how to use it at this link.
They are much more reasonable at Michaels Arts and Crafts. The one pictured above retails for about $13.00 at Michaels and I got it on sale for $9 last week! But the drawback is only one size of corner AND only one tile at a time.
It might be worth the extra money for the fancier one if the rounded corners is important to you and if you are a CZT teaching classes.