ShopDatabase

using System;
using System.Collections.Generic;
using System.Linq;

public class ShopDatabase
{
    public static void Main()
    {
        string input;

        var products = new Dictionary<string, Dictionary<double, int>>();

        while ((input = Console.ReadLine()) != "stocked")
        {
            var tokens = input
                .Split()
                .ToArray();

            var productName = tokens[0];
            var productPrice = double.Parse(tokens[1]);
            var quantity = int.Parse(tokens[2]);

            if (!products.ContainsKey(productName))
            {
                products[productName] = new Dictionary<double, int>();
                products[productName].Add(productPrice, quantity);
            }
            else
            {
                products[productName].Add(productPrice, quantity);
            }
        }
        double totalPrice = 0d;
        foreach (var currentProduct in products)
        {
            var productName = currentProduct.Key;
            var lastProductPrice = currentProduct.Value.Keys.Last();
            var sumOfQuantities = currentProduct.Value.Values.Sum();
            var finalPricesForTheCurrentProduct = lastProductPrice * sumOfQuantities;
            Console.WriteLine($"{productName}: ${lastProductPrice:f2} * {sumOfQuantities} = ${finalPricesForTheCurrentProduct:f2}");
            totalPrice += finalPricesForTheCurrentProduct;
        }
        Console.WriteLine("------------------------------");
        Console.WriteLine($"Grand Total: ${totalPrice:f2}");
    }
}