Australian firm Kogan.com is demanding an additional surcharge of 6.8% on all goods purchased through the previous generation web browser.
The company's chief executive Ruslan Kogan explained that the charge was to cover the cost of backwards compatibility. Although only 3% of customers use the software, his IT team must make necessary adjustments to facilitate it.
He told BBC News: "I was constantly on the line to my web team. The amount of work and effort involved in making our website look normal on IE7 equalled the combined time of designing for Chrome, Safari and Firefox."
Kogan went on to say that his aim is to encourage users to update to a more recent version of the Microsoft programme or switch to a different browser. Customers are said to have reacted positively to the policy, with some commending it via Twitter.
IE7 was released in October 2006, shipping as the default browser for Windows Vista and Windows Server 2008.