The board shall promulgate rules governing the assessment of costs against a licensee or other person found by the board to have violated any provision of this chapter. The costs assessed by the board may include only those costs directly related to the prosecution of the charges against the licensee or other person, including investigatory costs where appropriate. The board shall determine the appropriate amount of costs, if any, to be assessed in a contested case. These costs shall be reasonable and proportionate in light of the violation committed by the licensee or other person.