A polite way to say that you don't like something is to say, "I don't care for it, thank you.", or "I don't care for any, thank you.".  These phrases can be modified to fit almost any situation.

Examples:

John: "Here, have some of my chocolate!"

You: "I don't care for any, thank you."

John: "Are you coming to the rock concert?"

You: "No, I don't really care for rock music.  Maybe next time."

John: "I love bananas, don't you?"

You: "I don't really care for them.  I prefer oranges."

Basically it is more polite to say, "I don't care for . . . .", than to say, "I don't like . . .", especially to someone you want to make a good impression on :)

you actually answered your question.

when you don't like something you will say I do not like it.