Problem about Rotating the Character

So this is an isometric game...And I already have made a script, that handles the rotation of the character.Basically wha I want is interpolates/transition when rotating the character,so inside the FixedUpdate:

 if (transform.eulerAngles.y != targetDir) {
             if (transform.eulerAngles.y >= targetDir+(threshold) || transform.eulerAngles.y <= targetDir-(threshold)){
 
                 if (transform.eulerAngles.y < transform.eulerAngles.y-targetDir){
                     transform.Rotate(-Vector3.up*turnSpeed,Space.Self);}
 
                 if (transform.eulerAngles.y > transform.eulerAngles.y-targetDir){
                     transform.Rotate(Vector3.up*turnSpeed,Space.Self);}
             }
             else{
                  transform.eulerAngles = new Vector3(0,targetDir,0);}}

And whenever I press a key(the controls) I got something like this:

 if (Input.GetKey("w")){
             targetDir = 45f;

But the problem is...for example the current rotation is equal to 315(facing left) and I press the W key(which sets the targetDir = 45f) the rotation interpolates from 315 to 225 to 180 to 45 In SHORT COUNTER-CLOCKWISE.Well it's much simpler and better if it goes clockwise right? But I want it to rotate to it's nearest 45 degree...

The reason why I don't use lerpAngle for this,is because it's not accurate,I mean sometimes it's stuck like 44.9999 something like that... Any help?Thanks