The people of the City reserve the power to direct legislation by initiative and, in the exercise of such power, may propose any ordinance not in conflict with this charter or state law, except an ordinance appropriating money or authorizing the levy of taxes or an ordinance repealing an ordinance appropriating money or levying taxes. Any initiated ordinance may be submitted by a petition signed by registered voters of the city equal in number to at least twenty (20) percent of the number of registered voters residing in the city at the time of the last regular city election.