Check when multiple coroutines are all done

So I am making a dice rolling game, every turn the game generates between 1 and 3 dice that "roll" with a coroutine.

I am trying to find a way to check when all the dice are done rolling to do something.

My dice code (attached to each dice object created):

public class Dice : MonoBehaviour {

    // Array of dice sides sprites to load from Resources folder
    public Sprite[] diceSides;
    public GameObject DiceObject;
    public int finalSide = 0;
    public bool doneRolling = false;

    // Reference to sprite renderer to change sprites
    private SpriteRenderer rend;

    public  void Awake() {
    suspect = GameObject.Find("suspect");
    }
    // Use this for initialization
    private void Start () {

        // Assign Renderer component
        rend = GetComponent<SpriteRenderer>();

    }
    
    // If you left click over the dice then RollTheDice coroutine is started
    public void Rolling()
    {
        DiceObject.SetActive(true);
        StartCoroutine("RollTheDice");
    }

    // Coroutine that rolls the dice
    private IEnumerator RollTheDice()
    {
        // Variable to contain random dice side number.
        // It needs to be assigned. Let it be 0 initially
        int randomDiceSide = 0;

        // Final side or value that dice reads in the end of coroutine

        // Loop to switch dice sides ramdomly
        // before final side appears. 20 iterations here.
        for (int i = 0; i <= 20; i++)
        {
            // Pick up random value from 0 to 5 (All inclusive)
            randomDiceSide = Random.Range(0, 5);

            // Set sprite to upper face of dice from array according to random value
            this.GetComponent<Image>().sprite = diceSides[randomDiceSide];

            // Pause before next iteration
            yield return new WaitForSeconds(0.05f);
            doneRolling = true;
        }

        // Assigning final side so you can use this value later in your game
        // for player movement for example
        finalSide = randomDiceSide + 1;

    }
}

Now what would be the best way to check when all the dice created are done rolling and trigger another script at that time?

I was thinking about creating another game object that would be a parent of all the dice and do something like:

public class diceRollerCheck : MonoBehaviour
{

    public void checkIfDiceAreDoneRolling(){
        allDiceAreDone = false;
        while(allDiceAreDone == false){
            foreach (Transform child in this) {
                if (child.GetComponent<Dice>().doneRolling == false){
                    allDiceAreDone = false;
                }
                else{
                    allDiceAreDone = true;
                }
        }
    }
}

(This obviously doesn't work but that's the idea)