No, it's not an April Fools' joke unfortunately. Today, Hayward's sales tax--together with that of San Leandro, Union City, and Albany--increases to 10-percent, the highest in the state. The increase is a result of voters approving County Transportation Measure BB this past November. (Hayward's sales tax rate had just previously increased from 9- to 9½-percent this past October as a consequence of Measure C.)
El Cerrito and four Los Angeles communities share our top tier tax status. At 10-percent, we now have a higher sales tax rate than 99-percent of the nearly 1,800 communities listed on the State Board of Equalization's website.
Approximately 500 California communities have a sales tax rate of 7½-percent--the State's base rate. What's the difference? 2½-percentage points obviously, but in more tangible terms: a $30,000 vehicle purchased and registered in a city having a 10-percent sales tax rate will cost $750 more in sales tax than one purchased and registered in community having a 7½-percent rate--an appreciable difference.
For a breakdown of Hayward's sales tax composition, see this previous post.