If a disagreement between a seller and a buyer or the legal representatives of both or either arises over the percentage of butterfat contained in any quantity of milk sold or offered for sale at the request of the owner and in the owner’s presence, a sample of the milk obtained as provided in section 4.1-25-27 and mutually agreed upon by the interested parties as being a representative sample must be sealed and mailed by the buyer to the office of the commissioner. Each sample mailed to the commissioner must include a statement giving the name and address of the seller and the buyer of the milk in question, the net weight, the percentage and amount of butterfat contained, the price per pound [.45 kilogram] for butterfat, and the amount of money paid or offered in payment for the same and bearing the signature of the seller and the buyer. The commissioner shall determine the percentage of butterfat contained in the sample and shall report of the result in triplicate, the original to be filed in the commissioner’s office, one copy to be sent to the seller, and one to the buyer of the milk. The percentage of butterfat determined and reported constitutes the “official butterfat test” and is the basis on which final settlement must be made. The fee for the official butterfat test and any other tests required must be in an amount as set by rule of the commissioner, considering the actual costs of the test, and the fee must be mailed to the commissioner at the time of forwarding the sample for the official butterfat or other test.