Chief Executive Ruslan Kogan introduced the tax due to the time and effort it takes his web team to render the website into an antique browser. Even though only 3% of his customers used the old version of the browser, his IT team had become preoccupied with making adaptations to make pages display properly on IE 7.
The tax is to encourage users to use an updated version of Internet Explorer or use a different browser.
IE7 was launched in 2006, but since then Microsoft has released two major updates to the software.
The launch of Internet Explorer 10 is due in the autumn.