Minnesota treats it funny, at some point last year all of the employer paid tuition benefit for employees was taxable in the state, when even the Feds let you deduct the first $5,250, although I think this was fixed.
I'm not sure if this is your specific case but although it isn't taken into account for actual income tax purposes, Minnesota definitely adds in tuition and fees as the "nontaxable income" line when it comes to applying for the renters/property tax refund to up your adjusted gross. It was the only time I saw it but I use to have grad students and post docs complain about come tax time when I did payroll, although that was 10 years ago.
http://www.revenue.state.mn.us/Forms_and_Instructions/m1pr_inst_14.pdf Page 8 lists the nontaxable income. It's all types of tuition, employer paid, waived and scholarship.