The download button opens the iTunes App Store, where you
may continue the download process. You must have iTunes installed with an
active iTunes account in order to download and install the software. This
download may not be available in some countries.
From Carl Banks:
A clean & interactive tip calculator built for life's most common tasks. Choose among six everyday services for customary gratuities. Adjust your tip amount based on the quality of your service Easily split the bill with a parties of two or more Not satisfied with a particular preset? Gratuity is fully customizable, where settings for each venue are left at your full discretion.
Gratuity now has @3x image support for iPhone 6+. Settings now auto-save between views. Options to round can now be found in "General Settings". The double tap bug for rounding the total amount is now fixed.