Isometric mouse cursor snapping

MouseCursor.cs

void Update()
{
    RaycastHit hit;
    Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);

    if (Physics.Raycast(ray, out hit, 100, FloorLayer)) {
        Transform objectHit = hit.transform;

        if (SnapToGrid) {
            var newPos = new Vector3(Round(hit.point.x, GridSize), _yOffset, Round(hit.point.z, GridSize)); 

            if (_targetPosition != newPos) {
                Tween.Position(transform, newPos, TweenSpeed, _yOffset, Tween.EaseOut);
                _targetPosition = newPos;
            }                
        } else {
            transform.position = new Vector3(hit.point.x, _yOffset, hit.point.z);
        }
    }
}