Oklahoma sales tax applies to all sales (or rentals) of "personal tangible property" as well as the rendering of services like transportation, meals, and parking. (For details, see References, Oklahoma Tax Commission -- Taxes, Sales Tax.) Specifically, if property can be "seen, weighed, measured, felt or touch" or is in any other way perceivable (includes things like electricity and computer software), then the sale of it is taxable in Oklahoma---unless there is an exception. The sales tax rate is 4.5%.
Oklahoma has a small number of items that aren't subject to the state sales tax. Some consumer products aren't subject to the tax: prescription drugs, residential electricity and gas (though these might be subject to local county or city sales taxes), motor vehicles, and the fuel for motor vehicles. There are also exceptions for the agricultural industry. "Exemptions granted commercial agricultural operations include farm machinery and replacement parts, feed, seed, plants, fertilizer, pesticides, livestock medication, and a wide variety of purchases to be incorporated into agricultural buildings, machines or systems." (Quoted from References, Oklahoma Tax Commission -- Taxes, Sales Tax.)
If your business or institution sells tangible personal property continually, you need to have a Sales Tax Permit. If your business sells personal property only occasionally, you don't need a Sales Tax Permit, but you will need to file a Sales Tax Report for each sale. Indicate on it that the sales are "casual." You can obtain a Sales Tax Permit through the Oklahoma Tax Commission. The Application for Sales Tax Permit is available on the Tax Commission's website. (See References)
Local county and municipal governments may also levy a tax on the same items that are taxed by the state. Most local sales tax rates are set at between 2 and 3%. Counties with fewer than 300,000 residents can levy a sales tax of up to 2%. Counties with greater than 300,000 residents can only levy a tax up to 1% to raise money for public works in conjunction with the US government.
Certain other items are subject to various special taxes in Oklahoma. Any vehicle rental of fewer than $90 is taxed at 6%. This tax is in addition to the state sales tax due on all sales, included rentals. In other words, in Oklahoma, the total tax you'll pay to rent a vehicle for fewer than 90 days is 10.5% plus local county and municipal taxes.
Another related tax is the Strong Beer Tax. This tax charges wholesalers $12.50 per 31 gallon barrel of beer that is more than 3.2% alcohol by volume. There is also a tobacco tax, a tourism tax, and a special fuel tax (for fuels like LPG). Obtain more details and a schedule of fees from the Oklahoma Tax Commission. (See References, Oklahoma Tax Commission -- Taxes.)
