In certain instances FoxyCart calculates the California sales tax rate incorrectly. Perhaps only the zip code is used for sales tax calculation instead of the whole address. For example, this address should be 7.5%, per the California State website, https://maps.gis.ca.gov/boe/TaxRates
[FULL ADDRESS REDACTED —@brett]
However, FoxyCart calculates the rate as 8.5%, which is incorrect (that is the rate for Carmel-by-the-Sea but not Carmel). Let me know and I can provide a link to the receipt and website for this instance.
I have FoxyCart set to tax-type "Region", and region set to California with "tax is calculated automatically" set to Yes.