Never bothered measuring any of this but for those of you who need the numbers, a properly tuned and calibrated machine should get to a resolution of  between 0.075mm and 0.13mm. This holds true for any GT2 belt driven machine running 20 tooth GT2 gears.
In real life, the bits you use and level of micro stepping employed on your drivers are perhaps more important than the numbers. The example below was done with a 0,3mm bit. – Thanks to Nic Mossmer for the pics