I am creating a parametric part that has a linear rail bolted to it.  The rails come in 2mm increments.  I have the length of the Rail Pocket ("RAIL POCKET@Sketch12") and I want to round down to the closest even number.  For instance, if the pocket is 84.912mm, I want it to round down to 84mm.  To do this, I am using the following equation:

RAIL LENGTH = (INT("RAIL POCKET@Sketch12"/2)*2 

84.912mm/2 = 42.456m