iMargin - The Ultimate Business Trading Calculator The most comprehensive margin calculator on the Apple App store, not only does it calculate margins, markups, and profits, but you are able to enter tax rates and calculate reverse percentages if required. Calculate your - profit margin, - markup % - gross margin - reverse tax percentages Be able to preform quick and accurate calculations without having to remember any formulas. Also has the option of adding tax (GST / VAT) to calculations. Easy, Stylish and Modern App Design, an essential too for all business people and entrepreneurs.