As of August 2015, sales tax charts for states are available at the Sales Tax Institute website, notes the organization. The Sales Tax Institute separates the local taxes from the base state tax. The Sales Tax Clearinghouse also has a chart that provides the rates both separately and together.
The state with the highest sales tax rate in 2015 is California, with a rate of 7.5 percent after combining the state-wide county sales tax and the base sales tax, explains the Sales Tax Institute. Local rates are added, which increase the total paid for sales taxes in each city or municipality. Montana, Alaska, Oregon, New Hampshire and Delaware do not have sales tax.