According to my trick book, "roll over" is an intermediate-level trick. I've been having a lot of trouble training Thor with this one, so I did some research on the web. Apparently it can be tough for some dogs to learn. Thor is like your guy, he doesn't like to be rolled.
I've started with treating him when he rolls over on his own, which he does when he's playing.
You might want to google it, because there are a couple different methods.
I know I'm not giving up. Thor is soooo cute when he High-Fives, I can't wait for him to get Bang.