Truth be told, the only places I've seen that will pay you incrementally by the minute for anything out of the 9-5 will also dock you incrementally by the minute for taking too long of a lunch break, and count the number of bathroom breaks you take.

For salaried work, I don't think it should matter if you show up anytime within 1 hour of the start of business so long as no one is relying on you to be there (e.g. for a meeting or to work hand-in-hand with you).