NEWARK (KCBS) – When sales taxes go up Saturday April 1, check your receipts. In some Bay Area cities and counties, the rate will approach double-digits.

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The Bay Area city coming closest to a 10 percent sales tax rate is Newark, where from Saturday on, consumers will pay 9.75 percent.

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In the Napa County town of St. Helena, sales tax rates are going up from 7.75 percent to 8.25 percent.

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Voters approved new sales taxes in 42 California cities and seven counties, with hopes of fixing potholes and parks and other local concerns.

Jon Coupal with the Howard Jarvis Taxpayers Association, a perennial critic of tax increases, says voters feel like they get the most accountability from local tax revenue.

“The inherent problem with sales taxes of course, is they tend to be horribly regressive, hitting the poor and working class harder because they spend on consumer goods as a percentage of their disposable income than do the wealthy,” Coupal told KCBS. “The millionaires in Silicon Valley probably don’t care what the sales tax is.”

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Meanwhile in Silicon Valley, rates are going up to 9 percent in Santa Clara County, 9.25 percent in Campbell and San Jose.