Percentage IValueConverter

PercentageConverter.cs

public class PercentageConverter : IValueConverter
{
  public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
  {
    var fraction = decimal.Parse(value.ToString());
    return fraction.ToString("P1");
  }

  public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
  {
    var valueWithoutPercentage = value.ToString().TrimEnd(' ', '%');
    return decimal.Parse(valueWithoutPercentage) / 100;
  }
}