Study Snap to Grid (Tutorial)
In GGB 6, the snap to grid option in Options->Advanced->Preferences-Defaults was unavailable https://help.geogebra.org/topic/in-the-new-version-how-do-i-disable-points-snapping-to-the-grid
hence I produced this based on the previous discussions in the Geogebra help forum threads.
https://help.geogebra.org/topic/snapping-options
https://help.geogebra.org/topic/snap-point-to-grid
https://help.geogebra.org/topic/point-snapping-not-to-grid
https://help.geogebra.org/topic/capturing-grid-through-script
However I just realised that the 29 Jan version of GGB6 has the snap to Grid feature again.