using System;

public class Program

{

    public static void Main()

    {

        for (int i = 370; i <= 380; i++)

        {

            string res = ((((double)i) + 5) / 10 * 10).ToString("N0");

            string exp = (Math.Round(((double)i) / 10, MidpointRounding.AwayFromZero) * 10).ToString("N0");

            Console.WriteLine($"{i} -> {res} -> {exp}");

            Console.WriteLine(((i + 5) / 10 * 10).ToString("N0"));

        }

    }

}

​