Odoo 10 CE adds the sales tax to the cost as defined in the product record.  This is how people in the U.S. are accustomed to it.  Taxes are added on top of the advertised price.  Odoo 12 seems to do the opposite.  We have the same price defined for the products in Odoo 12 as we do in Odoo 10.  And we have the same sales tax defined.  Odoo 12 adjusts the product untaxed price downward so that the total price = the defined price.  In other words, the defined priced is the taxed amount.  Is this a configuration option I missed, or is it a change in the way Odoo handles prices?