>I'm probably displaying my typically dense nature here, but why isn't this hardcoding a tax rate?
>
>>>App.Configuration.TaxRate = 0.05M;

I'm not entirely sure what you're referring to, but if it's Rick's config. class what it actually does is instanciate the configuration class (which sets all the fields to their default value, such as 0.05M), then checks to see if the config. values are already in the .config file. If they are, it loads them from there (updating/replacing values as necessary). If it doesn't exist, it writes them to the file. So it's not really providing a hardcoded value as much as providing a default value.