GST Calc allows you to calculate Goods and Service Tax. Input one of the exclusive GST price, GST, or inclusive GST price. The other two are calculated automatically. GST rate can be modified to any percentage. This software does not work as a conventional calculator.

Sidenote: At the point of posting this program has been marked as beeing freely available without costs. As this program is hosted with the AppStore the status might change. Authors like to publish their programs for free for promotion purpose and then make it commercial. Also it could happen that the author decides to take the program down.

http://appshopper.com/finance/gst-calc