Here in New York State, the sales tax is around 8% depending on which county you live in. So if you trade your $30,000 truck in on a $60,000 truck, you only pay sales tax on the difference, or $2,400 in sales tax. If you sell your truck to someone instead of trading it in, you then pay the sales tax on the full $60,000 of the new truck, or $4,800 in tax.