Seven states and the District of Columbia boosted their sales tax rates in 2009, up from the five states that did so in 2008 and one state in 2007, according to the annual sales tax rate report from Vertex, a Berwyn, Pa.-based company that provides enterprise tax solutions. Overall, Vertex says, the number of tax rate changes in 2009 was more than 30% higher than the average for the years 2000 to 2007.

Vertex attributes the rash of tax rate changes to the magnitude of states' budget woes, and notes that there are already more changes in the works this year. Delaware increased its rental rate as of Jan. 1, and state legislatures in Arizona, Maine, New Mexico and Washington are considering proposals to boost tax rates.

California now has the highest sales tax rate, at 7.25%, with seven other states close behind it at 7%, according to Vertex, which calculates the average state sales tax rate at 5.468%.