The Commissioner of Revenue Services may prescribe regulations and make rulings, not inconsistent with law, to carry into effect the provisions of this part, which regulations or rulings, when reasonably designed to carry out the intent and purpose of this chapter, shall be prima facie evidence of its proper interpretation. The commissioner shall, at least annually, and more often in his discretion, publish for distribution all regulations prescribed hereunder and such rulings as appear to him to be of general interest.