Tick Chart : retrieving how many tick has ticked

Hi, Thank you very much for reading my question .

Im using the tick chart and want to know when the bar closes, for example like in 500ticks chart , when the tick reaches 480 is there a way i can get that in data and so i can get ready for the bar closes . 

at the moment , im doing  :

   private int Current_Index;
        private int Tick_Counter;
        private double Bid;

        public override void Calculate(int index)
        {
            if (Current_Index != index)
            {
                Current_Index = index;
                Tick_Counter = 1;
            }

            if (Bid != Symbol.Bid)
            {
                Bid = Symbol.Bid;

                Tick_Counter += 1;
            }



            Chart.DrawStaticText("Tick Count", Tick_Counter.ToString(), VerticalAlignment.Bottom, HorizontalAlignment.Right, Color.Lime);

I dont know if this is robust .

Thank you very much