gistfile1.txt

void Main()
{
   for (int i = 0; i < 1000; i++)
   {
       foreach(var b in ValueToUsableTokens(5000000, ValidMoney)) {}
       //Bruno's implementation
	     //foreach(var b in GetDecimalQuantities(5000000)) {} 
   }
}

private static readonly decimal[] ValidMoney = 
                   new[]{50M, 20M, 10M, 5M, 2M, 1M, 0.5M, 0.2M, 0.1M, 0.05M, 0.02M, 0.01M};

public IEnumerable<KeyValuePair<decimal, int>> GetDecimalQuantities(decimal value)
{
    int count;
    foreach(decimal note in ValidMoney)
    {
        count = 0;
        while(value >= note)
        {
            count++;
            value -= note;
        }
        if(count > 0)
        {
            yield return new KeyValuePair<decimal, int>(note, count);
        }
        if (value == 0)
            break;
    }
}

public static IEnumerable<KeyValuePair<decimal, int>> ValueToUsableTokens(decimal value, params decimal[] tokens){

    for(var i = 0; i < tokens.Length; ++i){
        var quotient = (int)(value / tokens[i]);
        if(quotient > 0){
		   yield return new KeyValuePair<decimal, int>(tokens[i], quotient);
        }
        value = value - quotient * tokens[i];
    }
}