Wow, you have no concept of business. When you collect sales tax it is not 'income' subject to write offs. You have to keep a ledger of every penny you collect and send the entire amount to the franchise tax board for each state you collect sales tax. By comingling tax money with income you are committing a felony.
p.s. since the transaction crosses state lines it is interstate commerce and a FEDERAL crime.
Tax evasion only applies to federal taxes. While Congress has to power to regulate interstate commerce, taxes are a whole different ball game. Tax law is more regulatory than it is statutory. The feds come into play if I was collecting taxes in another state. A California resident collecting California sales tax does not constitute interstate commerce.
Sales taxes are state taxes and are regulated by state law. Also, for the crime of tax evasion to be supported by the evidence at either the state or federal, intent has to be demonstrated. This is why the large majority of tax offenses are not prosecuted as crimes, but are rather handles civilly through negotiating with federal, state, and local agencies that are owed back taxes due to error about how much the person who owes money will pay and a payment schedule.
You also have a poor understanding of California tax law. I, like all other California businesses, do not "turn over" sales tax collected to the Board of Equalization. It works differently here. Sales taxes on the sales of consumer goods are calculated accurately when my state tax return is filed. What I owe is paid at the same time as I pay all my other state taxes. The seller is not paying me to turn over their payment to the Board of Equalization, but is rather reimbursing me for what I will owe later when I file my taxes.
tl;dr version
In most other states, sales taxes are paid using the seller as a medium to turn the money over to the tax franchise board. In California, instead of that happening, the seller calculates all taxes owed, including sales taxes, at the same time they calculate all their other state taxes. The collection of sales taxes at the point of sale is merely to reimburse the seller for what they will later owe.