comparing with precision / decimal places

void Main()
{
    // for any pair of comparisons, there are numbers
    // for which they give different results
    var a = 5.0000005m;
    var b = 5.0000006m;

    Console.WriteLine(CompareRound(a, b));      // false
    Console.WriteLine(ComparePrecision(a, b));  // true
    Console.WriteLine(CompareScaleFloor(a, b)); // true
    Console.WriteLine(CompareDelta(a, b));      // true

    a = 5.0000001m;
    b = 5.0000002m;

    Console.WriteLine(CompareRound(a, b));      // true
    Console.WriteLine(ComparePrecision(a, b));  // true
    Console.WriteLine(CompareScaleFloor(a, b)); // true
    Console.WriteLine(CompareDelta(a, b));      // true

}

// do the numbers round to the same number
bool CompareRound(decimal a, decimal b)
{
    return Math.Round(a, 6) ==
           Math.Round(b, 6);
}
// do the first X significant digits coincide
bool ComparePrecision(decimal a, decimal b)
{
    return (float)a == (float)b;
}
// do the first X digits after the decimal point coincide
bool CompareScaleFloor(decimal a, decimal b)
{
    return Math.Floor(a * 1000 * 1000) ==
           Math.Floor(b * 1000 * 1000);
}
// is the absolute difference lower than delta
bool CompareDelta(decimal a, decimal b)
{
    return Math.Abs(a - b) < 0.000001m;
}