I'd be on the phone with them in the am.....by law, max sales tax is 8.25% - the state sales tax rate is wrong, and I'd suspect the other two are, as well. State sales tax rate is 6.25%
My math shows 67.99 plus 13.55 equals 81.54. 81.54 times 6.25% equals 5.096, or 5.10.
Their rates and math are perfect