Sales to governmental entities that are exempt from the sales tax imposed by chapter 6 of this title, and sales of fuel to a qualified farmer or nurseryman, as defined in § 67-6-207 for agricultural purposes, as defined in § 67-3-103, shall be exempt from the tax imposed by this part. Sales of dyed diesel fuel taxed per gallon by § 67-3-202 are exempt from the tax imposed by this part.