Each person engaging or continuing in a business subject to the tax authorized by this part, and each casual sale, storage, use, or other consumption (sales or use) in this state that is subject to tax, shall add the sales or use price and collect from the purchaser the amount due by the taxpayer because of such sale or use. It shall be unlawful for any person subject to the tax to fail to refuse to add the sales or use price and to collect the tax from the purchaser.
It shall be unlawful for any person subject to the sales or use tax to refund or offer to refund all or any part of the amount collected or to absorb or advertise directly or indirectly the absorption or refund of any portion of the tax.