Marlin manual Bed leveling Leveling increment tweaking

Using a Makerfarm Pegasus 8 which in turn is Using Marlin Firmware 1.x, trying to improve my accuracy and was wondering if there is a way to tweak my setting for the manual leveling process.When performing a manual bed level, when i turn the knob the x carriage moves up or down at .5mm increments (I think) is there anyway i can lower the number to .25mm or .1mm.Perhaps I'm being anal, but I like to be as close to possible when running the process.Thanks