This doesn't appear to be correct.
For Example Mississippi has a combined tax rate of 12.21%, which is 13.5% higher than the national average, and ranks very low in educational attainment.
Below are the top ten in highest taxes and highest % of population with a Bachelors Degree (in many cases the areas with high rates of bachelor degrees have lower rates of high school grads.)
Highest Taxes: IL, CT, NE, NY, RI, WI, OH, IA, NJ, MI, PA, KS
Highest Education Rate: DC, MA, CO, MD, CT, NJ, VA, VT, NH, NY, MN
Link Taxes
Link Education