At the time of this article, the following are the fees required for each type of registration:
Electronic registration, single application (one work by one author): $45
Electronic registration, standard application: $65
Paper registration, Form TX: $125
Note, however, that the filing fees are subject to change; you can check the appropriate fees here.
Registering your copyright with the US Copyright Office is a quick and easy process. Registration can all be done online, or, if you prefer, you can mail in a print copy of your copyright application instead.