tax rate change but do not change gross

hi,
recently the tax rate in ireland changed back from 21.5% to 21%
we need to change the tax back to 21% but that will effect all the gross prices on the store - the retail prices to the customers.
Is there a way to change this so the gross price will remain the same but the net price will change back?

I did this in January over in the UK , I used easy populate to download all the products to Excel , did a quick calc to work out the new Nett prices , then re uploaded and switched the tax back to 17.5% appart from a few rounding errors it was pretty much spot on ! If you didn't want to use easypopulate , you could dump the table straight out of myphpadmin , change the prices and reupload.

If you want the retail price to stay the same then:

newnet_price * 1.21 = old_net_price * 1.215
therefore newnet_price = old_net_price * 1.215/1.21
or newnet_price = old_net_price * 1.004132231405

Backup your db

run sql on your db:

update products set products_price = products_price1.004132231405, products_price_sorter = products_price_sorter1.004132231405

Then adjust the sales tax amount to 21% under the admin/location/tax rates