Of course laws vary state to state. To keep it simple, forget the paid holiday because if that is your company policy (8 hrs at straight time for a holiday), then you just add that holiday "pay" to the paycheck. As an example, if July 4 was on a Saturday (not a regular work day for us), and we worked the full Monday thru Friday, 40 hr week, the employee would get 40 hrs straight time plus 8 holiday. However if we decided to let them take off on Friday the 3rd, their paycheck would be 32 hrs plus 8 holiday resulting in a full paycheck.
Now, if we ask them to work on that Friday that everyone else has off, we would pay 1.5, although we are not required too. If we had decided the company would work Friday the 3rd and employee had 40 hours, and was then called in to work on Saturday the 4th, they would be paid 1.5 for the hours they work, plus get the holiday pay. So, some folks look at that as 2.5 but if your already giving the 1 as holiday benefits, then you are paying 1.5 for overtime as required.
This is partly Fed and partly state (Arkansas), so may not apply to you.
I lean towards the generous side when I ask an employee to work a holiday. Especially one as important as Independence Day. Without that one, we probably wouldn't have any of them