You can fine-tune the placement of graphic objects by nudging them into place with the keyboard arrow keys. The nudge distance works independently of the object grid.

Select a nudge increment by clicking the Nudge tool  button.

The Nudge list has preset values. For 6/inch scanners, you have values of 25/300th (half of column width) or 1/12th inch and 5/300th. For 5/inch scanners, those change to 30/300th and 6/300th. You can set your own Horizontal and Vertical distances. You can also select two objects and set Nudge to the distance between those objects.