Fiskars makes a great squeeze punch for rounding corners. I like it because I can see the corner being snipped off, so there is no risk of cutting the corner off crookedly (is that even a word? ) It's also lighweight and small, fits right into my crop bag.
My first corner rounder just came from the office supply section! You don't need anything too fancy - just a corner rounder punch. You can find them anywhere. I love using mine! I also have one that makes a scalloped corner!
I have a Fiskars (?) corner rounder- it's a hand punch and it's blue. I can only punch one page at a time but it works for me- I use it on pictures and cs and it's fine. Your hands will get tired after a few pages. I have seen it at J's and M's- think I got mine at J's
I have the Creative Memories corner rounder...I like it better than any other that I've used. They also have a scalloped corner punch, but I do not like it as well.
I had a corner rounder from WM...it was green I think?? It was a piece of trash! Cut just a few times and then it was so dull it wouldn't cut anymore. To me it was hard to get lined up. The CM one is much more sturdy and I've used it lots of times and it is still sharp as ever!
The creative memories corner rounder is a great must have tool. If it does start to get "dull" and not work, use a small piece of wax paper or tinfoil and insert into the tool and round the corner like you would with a photo. This will sharpen it up again.