It depends.... It's all relative to the posted speed limit so obviously if the speed limit is 55 and you're going 100, the fine is based on going 45 mph over the limit whereas if the speed limit were 80 (parts of Texas, N or S Dakota, as I understand), you're only 20 mph over. In Ohio, some courts simply have a chart - 1-10 mph over = $ XX, 11-20 mph over = $YY, and so on for the fine. You can pay the ticket over the phone or online too although some courts have something like "30+ mph, court appearance required...".
We also have what's called "reckless operation" citation in Ohio and this is solely at the police officer's discretion. The same officer could cite a driver for speeding at 30+ but that person was going with the flow of traffic (it's still speeding) while they could cite a driver going 20+ mph but weaving in and out of lanes with reckless operation.