Sometimes I use an emery board after trimming. It doesn't take much work to file the sharp spots off. I have tried an electric pet nail file (grinder), but I think using a nail cutter and an emery board is a lot easier.
Both my bunnos past and present i tried to file their nails after trimming them. With Musti it was no problem since he was so sweet and docile, he even quite enjoyed trimming and filing and combing-pretty much any attention and he would kiss you in return.
Storm on the other hand is well, like a storm. I'm not sure if it's because he hasn't completely gotten used to us yet or if it's just his nature but he absolutely despises interacting. When he went for a check at the vet i requested his nails to be snipped at the tips 'cause they were unbearably sharp and pointy. The vet, his assistant and me all had to hold Storm still so that his nails could be trimmed. My hands were a mess after that but i like him so i didn't mind.
I tried a couple of files. Bun nails are usually much stronger than human ones so the soft paper one failed on me instantly. I tried out a bit rougher one and that failed too. A glass ome didn't work for Musti but it might work for some other bun. Now my granny gave me a metallic medium one tk see if it works.
I wouldn't try too coarse ones either.