I love the name. I'm not sure what I love about it. The sound. It sounds strong and manly. And the spelling with the two "c"s looks cute. And that is why I don't like the variant Rocko. It seems so "unnatural"? The "ck" doesn't fit here, I think.
Somehow this name makes me think of a really muscular, tanned macho guy from Southern Europe or South America who is dumber than a box of rocks and is the lifeguard and lover of some rich middle-aged woman who finds him an idiot but loves his sex appeal. It's such a tacky name, and it sounds more like the name for either a criminal or a dumb but (in some women's opinion) sexy mach tool.
Roll your "R." "O" is as usual, "Oh." Both "CC"s are hard-- and both must be distinctly pronounced. That task is most easily accomplished by placing extra emphasis on the letter before ("O") and slowly strolling through. Finish off with "Oh." [noted -ed]
I'm beginning to like this name. I think it's strong, but has a childlike innocence. Cute on a boy, handsome on a man. I also like the simplicity mixed with rarity.