Registration as a minister is not the same as registering to be a wedding officiant or to solemnize weddings. Being a wedding officiant is a liaison between the couple and the state and the state may have specific requirements for your as a minister to register.
Many states do not implicitly require ministers to register to perform religious duties, as the constitution clearly state the separation between church and state. You should consider contacting your local chamber of commerce if you wish to start your own ministry and be sure that you have contacted any state or local governmental agencies for further questions.
Also see: "How to register as a wedding officiant"