For each brand and grade of commercial fertilizer and for each soil conditioner distributed in the State, the annual registration fee is $15 and the annual inspection fee is 25 cents per ton except: For each brand and grade of commercial fertilizer and each soil conditioner distributed in packages of 10 pounds or less, the annual registration fee is $30, notwithstanding any other registration or inspection fee; and For each brand and grade of commercial fertilizer and each soil conditioner distributed in packages of 10 pounds or less and in packages over 10 pounds, the annual $30 registration fee applies, and only the portion distributed in packages over 10 pounds is subject to the inspection fee of 25 cents per ton. Mixed-to-order, buyer’s mixture, or custom-mix fertilizer is exempted from the registration fee, but the inspection fee shall be paid. Distribution of fertilizer materials to manufacturers or exchange between them is exempted.