I'm 18 and made about $5k last year. My parents claim me on their return...if I read the regs correctly I do not have to file Is that true?

If you have a W-2 you do not "have" to file but if there are any amounts in boxes 2 or 17 of that W-2 you can file to get a refund of the tax withheld.   If your income was from self-employment then you are REQUIRED to file and pay self-employment tax for Social Security and Medicare.