Code to detect side of an object a point is on is offset

I am using a raycast to determine when a player has clicked on an object, so that they can connect two objects together. While I can just let them try to line up the objects, I think it would be better if they were able to "snap" the objects into a correct alignment.

Therefore, I have used the following code to do this: public Vector3 GetSide(Vector3 CheckPoint) { Vector3 Localized = transform.InverseTransformPoint(CheckPoint); Vector3 Direction = new Vector3();

         float XDifference = Mathf.Abs (Localized.x);
         float YDifference = Mathf.Abs (Localized.y);
         float ZDifference = Mathf.Abs (Localized.z);
         
         if ((XDifference > YDifference) && (XDifference > ZDifference))
         {
             if (Localized.x < 0)
                 Direction = -transform.right;
             else if (Localized.x > 0)
                 Direction = transform.right;
         }
         else if ((YDifference > XDifference) && (YDifference > ZDifference))
         {
             if (Localized.y < 0)
                 Direction = -transform.up;
             else if (Localized.y > 0)
                 Direction = transform.up;
         }
         else
         {
             if (Localized.z < 0)
                 Direction = -transform.forward;
             else if (Localized.z > 0)
                 Direction = transform.forward;
         }
         
         return transform.position + Direction * (transform.localScale.x + 0.01f) / 2;
     }

It mostly works, however instead of giving an exact point, it is slightly offset, so the attached part is not centered accurately. Any ideas as to why this is?

Thanks!