The second one is wrong. More common is: "That's fine with me."

It is ok for me. - Implies that "it" is okay only for you, example: "It's a secure building, so you can't enter, but it is ok for me." It is ok to me.- Implies that from your perspective, it is ok, example: "The critic hated that movie. It is ok to me." At least, that is how I would understand the two sentences. Hope this helps.