A 401k at 17 sounds like a great idea, but on second thought... do you have a savings account? You really want to have 5k or so in a savings account for emergencies first. Living with your parents is nice but once you get your own place and you have bills, and your car breaks down and you have to pay to fix it to get to work, that 401k won't help.
5% contribution is a great idea, but make sure you have emergency savings set aside first.
I've got 8k in a 401k but that didn't help when my transmission went out, or when my dog caught a nasty case of giardia and I got a nice 600 dollar vet bill.
Props to you for looking out for your future though, no one else is going to do it for you. Sounds like you've got a strong head on your shoulders so you've got a jump on most people your age.
Yes sir, I have a savings account that I'm adding on to.