Examinations shall be held at such times and places as the department shall determine. Examinations required on fundamental soil subjects may be taken at any time prescribed by the department. The final examinations may not be taken until the applicant has completed a period of soil classifying experience as provided in this chapter. The passing grade on any examination shall not be less than seventy percent. A candidate failing one examination may apply for reexamination, which may be granted upon payment of a fee established by the department of not less than ten nor more than twenty-five dollars. Any candidate for registration having an average grade of less than fifty percent may not apply for reexamination for a period of one year from the date of such examination.