Normally, this is considered to be a poor misspelling of Rockman X, which makes sense as the game's Chinese title (on the Game Boy, at least) is 波克人 (Luo Ke Ren, which apparently translates to Rockman. Strangely, in Google Translate, it's actually "Bō kè rén" and translates to "Polk Man.") One thing that crossed my mind, though, is that it's evident in the NES version that they seemed to try and make it more of an original title than planned. The manual mentions controls similar to the Game Boy version, yet it has completely unique gameplay, involving a boomerang weapon and the ability to glide in one of three directions to reach difficult places.
I've noticed that "ROC" has been used in at least two of their other games: Silent Assault (shown on a plane in level 3) and Millionaire (as the most expensive country you can buy.) R.O.C. happens to stand for Republic of China, which is another name commonly used for the country of Taiwan, and Taiwan happens to be where Sachen is located at. What am I trying to get at? What I'm thinking is that maybe, just maybe, Sachen, even in an indirect way, thought of having Rocman's name stand for "R.O.C. Man," AKA Republic of China Man. Think Captain America with this. It's a long shot, especially since Sachen didn't try to hide that it was inspired by Mega Man, and that they aren't the most fluent English speakers in the world (THANK YOU FOR YOUR COMING!) but hey, it's a thought. The name Rocman X is mainly used for the Chinese version of the game (Game Boy and Famicom,) while the English version uses Thunder Blast Man (Game Boy and NES,) so it would make sense for Asian audiences to relate to R.O.C. Man than English audiences (keep in mind Sachen has made English and Chinese equivelants for a lot of their games.)
Hey, it's a ridiculous idea, but it's a possibility. Sachen has proven, even in their later TC-XXX games, which are more knock-off-ish than their earlier titles, that they can be more clever than they appear (Q-Boy, anyone?)