See sibling post for links, but the short answer: you can use 12 pentagons, strategically interspersed. Like a (soccer) football.

edit: Oops, that only explains the tiling. For explanations of how the hierarchy descends, Dr. Sahr produced some GIFs that give a little bit of an overview of how the resolutions overlay: http://webpages.sou.edu/~sahrk/dgg/images/topogif/topogif.ht...