Book Orders - correction

namespace BookOrders
{
    using System;
    using System.Collections.Generic;

    public class BookOrders
    {
        public static void Main()
        {
            int n = int.Parse(Console.ReadLine());
            var books = new List<double>();

            for (int i = 0; i < n * 3; i++)
            {
                books.Add(double.Parse(Console.ReadLine()));
            }

            double totalBooks = 0;
            double totalPrice = 0;

            for (int i = 0; i < books.Count; i += 3)
            {
                double tempBooks = books[i] * books[i + 1];
                double tempCost = GetDiscountedPrice(books, i);

                double tempPrice = tempBooks * tempCost;
                totalPrice += tempPrice;

                totalBooks += tempBooks;
            }

            Console.WriteLine(totalBooks);
            Console.WriteLine("{0:F2}", totalPrice);
        }

        private static double GetDiscountedPrice(List<double> books, int i)
        {
            double tempCost = books[i + 2];

            if (books[i] >= 10 && books[i] <= 19)
            {
                tempCost *= 0.95;
            }
            else if (books[i] >= 20 && books[i] <= 29)
            {
                tempCost *= 0.94;
            }
            else if (books[i] >= 30 && books[i] <= 39)
            {
                tempCost *= 0.93;
            }
            else if (books[i] >= 40 && books[i] <= 49)
            {
                tempCost *= 0.92;
            }
            else if (books[i] >= 50 && books[i] <= 59)
            {
                tempCost *= 0.91;
            }
            else if (books[i] >= 60 && books[i] <= 69)
            {
                tempCost *= 0.9;
            }
            else if (books[i] >= 70 && books[i] <= 79)
            {
                tempCost *= 0.89;
            }
            else if (books[i] >= 80 && books[i] <= 89)
            {
                tempCost *= 0.88;
            }
            else if (books[i] >= 90 && books[i] <= 99)
            {
                tempCost *= 0.87;
            }
            else if (books[i] >= 100 && books[i] <= 109)
            {
                tempCost *= 0.86;
            }
            else if (books[i] >= 110)
            {
                tempCost *= 0.85;
            }

            return tempCost;
        }
    }
}