Move player to mouse position never go to exact position

Hello, I hope title is good to explain my problem i use this code to move my character to mouse position when i click. i search arround the forum to find for similar problem but nothing.

 void onTouch ()
     {
         if(Input.GetMouseButtonDown(0))
         {
             if(!one_click) // first click no previous clicks
             {
                 one_click = true;
                 
                 timer_for_double_click = Time.time; // save the current time
                 target = Input.mousePosition;
                 target = Camera.main.ScreenToWorldPoint(target);
                 target.z = 0f;
                 speed = 2f;
             } 
             else
             {
                 one_click = false; // found a double click, now reset
                 speed = 4f;
             }
         }
         if(one_click)
         {
             // if the time now is delay seconds more than when the first click started. 
             if((Time.time - timer_for_double_click) > delay)
             {
                 
                 //basically if thats true its been too long and we want to reset so the next click is simply a single click and not a double click.
                 
                 one_click = false;
                 
             }
         }
         transform.position = Vector3.Lerp (transform.position, target, speed * Time.deltaTime);
     }

ther problem is that when i click the character start move fast i think with 2f but i think when is near to the position slow down... so move so slow is like he arrived at the position but x and y change for a long time changing decimals only ex. mouse position 5,5,0 character position after fast move 4.69999.... this number increas slowy. My character is like move on ice... :/

any ideas?

Thanks !

Edit Solution !!!!

Now i find the solution... i post it here if someone have the same problem.

 void onTouch ()
     {
         if(Input.GetMouseButtonDown(0))
         {
             if(!one_click) // first click no previous clicks
             {
                 Debug.Log(Camera.main.ScreenToWorldPoint(Input.mousePosition));
                 one_click = true;
                 
                 timer_for_double_click = Time.time; // save the current time
                 target = Input.mousePosition;
                 target = Camera.main.ScreenToWorldPoint(target);
                 target.z = 0f;
                 speed = 10;
             } 
             else
             {
                 one_click = false; // found a double click, now reset
                 speed = 20;
             }
         }
         if(one_click)
         {
             // if the time now is delay seconds more than when the first click started. 
             if((Time.time - timer_for_double_click) > delay)
             {
                 
                 //basically if thats true its been too long and we want to reset so the next click is simply a single click and not a double click.
                 
                 one_click = false;
                 
             }
         }
         float step = speed * Time.deltaTime;
         transform.position = Vector3.MoveTowards(transform.position, target, step);
         //transform.position = Vector3.Lerp (transform.position, target, speed * Time.deltaTime);
         if(target == transform.position)
         {
             speed = 0f;
         }
     }