Thank you for keeping it professional, HW. I'm going to address taxes in general and then this case specifically.
Local sales taxes are charged for all items unless a tax exemption form is received prior to the close of the sale. If the truck you bought was located in AZ, for example, then you would pay the local sales tax for that area, not for your home state. This is because we have a physical location in that state where the item is being sold and are legally required by state laws to charge sales tax.
It's similar to going to a store in another state and making a purchase. You'll be assessed the local sales tax.
However, possession, control and risk of loss of any property purchased passes to the customer, or their representative, at the location of the sale. So the sales tax applies whether or not the intention is to transport the property to a location outside the state (and/or country) and whether or not the property is actually transported elsewhere.
This is all complicated by the fact that state tax laws regarding the sales taxation of vehicles vary by state. In some states, sales tax is collected by the seller and remitted to the state. In other states, the sales tax is not collected by the seller but is paid by the customer when they license, title or register the vehicle.
So it's possible for a vehicle that's purchased in one state, where sales tax is required at time of sale, to then be transported to another state where taxes are charged at time of registration.
In this case, the VA Motor Vehicle Sales and Use Tax rate is 3%, and we do not collect that tax. The Code of Virginia basically says that the purchaser pays the tax to the DMV when they title the vehicle: “§ 58.1-2404. Time for payment of tax on sale, use or rental of a motor vehicle. The tax on the sale or use of a motor vehicle shall be paid by the purchaser or user of such motor vehicle and collected by the Commissioner at the time the owner applies to the Division of Motor Vehicles for, and obtains, a certificate of title.”
If you were charged 5% for a vehicle you bought in VA, which is what I'm inferring from your post, then an error was made and I would advise you to contact Customer Service.