Fixing math in Get PWM methods

Changed around math in Get methods to try to get rounding error right.
If you're truncating a positive float to an int you can easily round it
by adding 0.5 to the float value.  Then anything under 11.5 will get
truncated to 11 and anything 11.5 and over will get truncated to 12 when
0.5 is added to it and then truncated.