while "you're welcome" is the standard response for 'thank you', you can also say, "my pleasure" or "don't mention it" or "no problem" or just what you've mentioned - "sure".
there's nothing to be worry of being rude when saying "sure" in response, so long as you're saying it in a polite manner (i.e. a smile on your face, standard tone of your voice, friendly eye contact, etc.)
:)