Use Your Own Credit Card Processor, or Ours
Here is a story from our own past. One registration system we used charged us 12% on payments because we used their credit card processor, and it would not let us use our own. On a convention with a few hundred attendees, that is real money that should have gone to the event.
Conference and Event Management lets you use your own credit card processor, so the rates you have already negotiated stay yours. If you do not have one, or would rather not manage one, you can use ours, with the payment types we accept and our rates shown up front.
Not everyone pays by card. Plenty of attendees, especially in clubs and associations, still prefer to mail a check. Offline payments via US Mail are part of the system, so those attendees can register the same way as everyone else.
Sales tax is figured line by line on the items that are subject to it, and attendees see what they owe before they pay. No surprises for them, and no surprises for you.