Finding the least amount of bills/coins for any monetary value (using common bills/coins, no $2 bill, 50 cent coin, etc)

ChangeCalculator.cs

public class ChangeCalculator
{
    public static Dictionary<decimal, decimal> GetUsdChange(decimal dollars)
    {
        return GetChange(dollars, new[] {100, 50, 20, 10, 5, 1, .25M, .10M, .05M, .01M});
    }

    public static Dictionary<decimal, decimal> GetChange(decimal amount, IEnumerable<decimal> denominations)
    {
        denominations = denominations.OrderByDescending(i => i);
        var dictionary = new Dictionary<decimal, decimal>();
        foreach (var denom in denominations)
        {
            var quantity = decimal.Truncate(amount / denom);

            if (quantity > 0)
                dictionary.Add(denom, quantity);

            amount = decimal.Subtract(amount, decimal.Multiply(quantity, denom));
        }
        return dictionary;
    } 
}