Federal excise taxes which are levied upon the manufacturer or retailer are not deductible from gross sales even though they are invoiced or added to the bill of the consumer/user as a separate item. The tax is part of the purchase price of merchandise sold by the retailer to the consumer, and the sales tax shall be computed upon the full selling price, which includes the federal excise tax.
Okla. Admin. Code § 710:65-19-102