To sell music online you may use RouteNote. It is a kind of aggregator to distribute music to various online music stores as well as to various music streaming services. The latter includes Deezer, Google Play Music and Spotify. Depending on the kind of distribution by stream or sale the revenues are either paid by sale or stream as well.
RouteNote offers two versions to distribute and sell music, a free and a premium version. The free version is based on revenue sharing. Using the premium version the seller gets the whole revenue. Furthermore both options differ regarding the required file format. At the free version mp3 is required. The premium version offers further formats and is currently starting to offer the option to upload high-res-audio. The option to be able to upload mp3 is something unique by the way as most services ask for wav files. To get further information and start selling your music visit the homepage of RouteNote.