Tax Calculator

using System;
using System.Collections.Generic;

public class TaxRule
{
    private Func<decimal, bool> isMatch;
    private Func<decimal, decimal> calculator;

    public TaxRule(Func<decimal, bool> isMatch, Func<decimal, decimal> calculator)
    {
        this.isMatch = isMatch;
        this.calculator = calculator;
    }

    public bool IsMatch(decimal value)
    {
        return this.isMatch(value);
    }

    public decimal CalculateTax(decimal value)
    {
        return this.calculator(value);
    }
}

public class TaxCalculator
{
    List<TaxRule> rules = new List<TaxRule>
        {
            new TaxRule(m => m > 40230, m => (m-40230m)*.45m + 10671.6m),
            new TaxRule(m => m >= 21241 && m <= 40230, m => (m-21240m)*.33m + 4404.9m),
            new TaxRule(m => m >= 14071 && m <= 21240, m => (m-14070m)*.30m + 2253.9m),
            new TaxRule(m => m >= 8661 && m <= 14070, m => (m-8660m)*.23m + 1009.6m),
            new TaxRule(m => m >= 5071 && m <= 8660, m => (m-5070m)*.14m + 507m),
            new TaxRule(m => (m < 5070), m => m * .10m),
        };

    public decimal CalculateTax(decimal value)
    {
        foreach (var rule in this.rules)
        {
            if (rule.IsMatch(value))
                return rule.CalculateTax(value);
        }

        return 0;
    }
}

[TestClass]
    public class UnitTest1
    {
        [TestMethod]
        public void Salary_Of_5000_Has_Tax_Of_500()
        {
            var salary = 5000m;
            var expected = 500m;

            TaxCalculator calculator = new TaxCalculator();
            var actual = calculator.CalculateTax(salary);

            Assert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void Salary_Of_5800_Has_Tax_Of_609_2()
        {
            var salary = 5800m;
            var expected = 609.2m;

            TaxCalculator calculator = new TaxCalculator();
            var actual = calculator.CalculateTax(salary);

            Assert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void Salary_Of_9000_Has_Tax_Of_1087_8()
        {
            var salary = 9000m;
            var expected = 1087.8m;

            TaxCalculator calculator = new TaxCalculator();
            var actual = calculator.CalculateTax(salary);

            Assert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void Salary_Of_15000_Has_Tax_Of_2532_9()
        {
            var salary = 15000m;
            var expected = 2532.9m;

            TaxCalculator calculator = new TaxCalculator();
            var actual = calculator.CalculateTax(salary);

            Assert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void Salary_Of_50000_Has_Tax_Of_15068_1()
        {
            var salary = 50000m;
            var expected = 15068.1m;

            TaxCalculator calculator = new TaxCalculator();
            var actual = calculator.CalculateTax(salary);

            Assert.AreEqual(expected, actual);
        }

    }