UPDATE:
Jim Saunders reports that 'rounding' is done. I guess that all that is really needed is for the documentation to state such.
The SET REFRESH command is documented as taking only integer values in each of its two arguments.
Neither of:
SET REFRESH TO 0.5
SET REFRESH TO 0.5, 0.5
... raises an error.
The first command above effectively leaves both arguments at their default values (0, 5) but the second example results in revised values of (0, 0).
I believe that any attempt to set either parameter to a non-integer value should result in an error.
This behaviour is identical in VFP6SP5 and VFP7SP1.