Decisions to make:Debt vs Retirement

I've mentioned before that we use our rental income to save for retirement but since we have not had tenants since October there has been no retirement savings.  For the 2011 year we have put aside $3600 which is $300 short of our 15% goal.  However, we do also set aside $25/month of our rental income towards taxes.  This year we owe no taxes (actually according to the government we have a loss of $600 on the rental) and therefore we need to decide what to do with the $225 of tax money.  I originally thought to just put it in the Roth IRA because we are not making the retirement goal however, we do have a lot of student loan debt and paying extra on that would make me happy.  Granted most of it is deferred and not earning any interest but about $5450 is accruing interest at 5.75%.  I am still leaning towards just putting the money in the Roth IRA but I have till April 15th to decide.