Usually (not for everyone, but a LOT), interns are "low income" in that they make 6mo salary which ends up being around $20k. Once you add in deductions (which are multiple, and you should LOOK for them), you end up w/around $16k income for a taxable year.
During your 6 months of intern year, you probably have W2 with ~2 deductions or so. By the end of the year you will have been "over taxed". Thus getting most of it (it being YOUR MONEY), back because you are low income bracket.
As always, this depends on you and your situation, state, debt, interest, mortgage, donations, etc, but almost (if not all), of our interns and my class as an intern, got ~100% of state and federal taxes back.