I would like to donate this code to OpenCart core as it is useful for many people.
I have already submitted a pull request (meaning submitted the code to core team).
Please vote at http://opencart.uservoice.com/forums/52387-general/suggestions/7405600-amazon-like-you-save to encourage the core team to include my code (this feature) in OpenCart core.
If you are running any promotions (Specials in OpenCart parlance), then it is a great idea to tell the customers not only what the regular and special prices are, but also what they are saving.
Following the example of Amazon, this extension add a savings notice "You save: $x (y%)" below the price on product page.
Please read documentation.
Support is at http://forum.opencart.com/viewtopic.php?f=131&t=84524
Because this is a vQmod, no core files are touched, and the changes should carry over to the next version.
I hope you enjoy this extension. If you'd like to donate, please PayPal to firstname.lastname@example.org