TipCalc is based on an existing iOS and Android sample but has been completely rewritten for Xamarin.Forms using XAML and data-binding. This new version now builds for iOS, Android, and the Universal Windows Platform.
TipCalc lets you type in a food-and-drink subtotal and a post-tax total from your restaurant bill and then select a tip percentage. It applies the percentage to the food-and-drink subtotal and adds the result to the post-tax total, rounded to the nearest quarter.
The calculations are handled in a TipCalcModel class, and the entire user interface is realized in XAML in the TipCalcPage.xaml file. Two data-binding value converters help massage the data between the data model and the XAML file.