Convert currency string to decimal?

How about this, but only works for one string value. So you need to get your string split by $ and then do the conversion while saving into the array or list

 using System.Globalization;
    //rest of your code

          string str = "$50,550.20";
          decimal decval;
          bool convt = decimal.TryParse(str, NumberStyles.Currency,
            CultureInfo.CurrentCulture.NumberFormat, out decval);
          if (convt) 
          Console.WriteLine(decval);
          Console.ReadLine();

Here is a simpler solution:

    public static decimal ToDecimal(this string str)
    {
        return decimal.Parse(str, NumberStyles.Currency);
    }

and the unit test:

    [Test]
    public void ToDecimal_Convert_String_To_Decimal()
    {
        Assert.AreEqual(1234M, "1234".ToDecimal());
        Assert.AreEqual(-1234.56M, "$(1,234.56)".ToDecimal());
        Assert.AreEqual(1234.56M, "$1,234.56".ToDecimal());
    }

Here is a method that most closely resembles the code you've provided

public static decimal Parse(string input)
{
    return decimal.Parse(Regex.Replace(input, @"[^\d.]", ""));
}

Here is an option that will support negative numbers, and will stop if it finds a second period value, thus reducing the number of strings it returns that are not valid decimal values. It also has a few other modifications not seen in the OP to handle additional cases your current code doesn't.

public static decimal Parse(string input)
{
    return decimal.Parse(Regex.Match(input, @"-?\d{1,3}(,\d{3})*(\.\d+)?").Value);
}