P.S. You have till midnight central time the next day to cancel your ticket. So if you've bought your ticket today regardless of most fare classes, you
should have till midnight central tomorrow to cancel without penalty. A charge will show up on your bill but will be credited back.
http://www.nwa.com/plan/guide03.html
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">If you purchase your ticket at the time you make your reservation, you can secure your ticket, the fare you've been quoted and a guarantee for a full refund without penalty fees if you cancel your reservation by the end of the next day (midnight Central Standard Time). If you don't cancel the reservation, however, you will not receive a refund unless you have purchased a fully refundable fare. </font>
aloha