Mathf.Round isn't working.

I have this script here:

using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI;

public class Score : MonoBehaviour { public Text score; public Text highScore;

 public float scoreCount;
 public float highScoreCount;

 public float pointsPerSecond;

 private void Start()
 {
     score = GameObject.Find("Score").GetComponent<Text>();
     highScore = GameObject.Find("HighScore").GetComponent<Text>();
     highScore.text = PlayerPrefs.GetFloat("HighScore", 0f).ToString();
 }

 private void Update()
 {

     scoreCount += pointsPerSecond * Time.deltaTime;
     score.text = scoreCount + Mathf.Round(scoreCount).ToString();

     PlayerPrefs.SetFloat("HighScore", scoreCount);

     //scoreCount += pointsPerSecond * Time.deltaTime;
     //scoreText.text = "Score: " + Mathf.Round (scoreCount);

 }

 public void MakeHighScore()
 {
     highScore.text = PlayerPrefs.GetFloat("HighScore", 0).ToString();
 }

}

I have been trying for ages to get it to work and now all that's left is for the score to be rounded. Can someone please help me figure out why it won't round "scoreCount"?