XAML
<Window x:Class="ComboBoxTag.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
<ComboBox
SelectedValue="{Binding Rate, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"
SelectedValuePath="Tag" Margin="0,0,306,295">
<!--
Tag is values of Rate enum -->
<ComboBoxItem Tag="Bad">Bad</ComboBoxItem>
<ComboBoxItem Tag="Low">Low</ComboBoxItem>
</ComboBox>
</Grid>
</Window>
C#
namespace ComboBoxTag
{
public enum Rate
{
Bad = 0,
Good = 1
}
}