As a practical matter, if you don't check the box, and your parents don't claim you, then there is no conflict and the IRS is unlikely to question it.
As a strictly legal/tax code matter, you may have to actually add up all your costs. Publication 501 has a worksheet that may be helpful.
Support you provide yourself includes money you earn that you use for your own support, and it includes student loans you take out in your name (this counts as support you provide to yourself because you have promised to pay the loan back.). Support your parents provide to you includes a percentage of the costs of running their home (if you are still considered to live there because you return home over summers, they keep a room for you, you haven't permanently moved out), and monetary support paid for your tuition, food, clothes, travel, and medical expenses. If they carry you on their medical insurance, the premiums count as support provided to you. Add everything up and see where it goes.
