AutoCAD 2012 MAC

I am having an issue with unit / dimension settings. I have noticed the the 2012 CAD for Mac wants to round up/down no matter what I set my scale, it always seems to round up/down a 1/16 of an inch. If I am drawing a fixture that requires a given dimension; example, 5'-2 1/2" height and I draw a line at that height; when I put a dimension to that line, sometimes it reads a 1/16" up/down (example 5'-2 7/16"). I have tried setting my units and dimension to the lowest tolerance and it still rounds up or down. 

Does anyone know how to solve this issue? Thanks

Jean Luc

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