My store store contains about 600 products, all with the same price. Now our Dutch tax rate has gone up from 19% to 21% I realize, I made a mistake. The change from 19% to 21% was easy, but instead of using the total amount included tax, I used the amount without tax, and I don't longer want that. So, how can I edit these 600 products (admin/commerce/products and content) all at once, instead of 1200 single changes?

Thanks very much!