I'm trying to prototype models of spaceships that could be built in a voxel based game(think Space Engineers). While this is fairly easy to do manually it would be much quicker if I could make all vertices snap to a 3D grid while extruding, scaling, etc. I know you can do this for individual actions, but is there a global setting? More precisely I want to ensure that the coordinates of any vertices are integer values.
Are you perhaps talking about the Snap to Grid tools?
You simply click to the magnet icon to enable that, pick your poison in terms of what you want to snap by (side-note: doing so by volume is fantastic when setting up rigs). Works in object/edit modes, and with all sorts of translation/scaling/rotating.
Edit: If you want to modify the increment size, try this answer.
Hope that helps!