Taxes weird between Firefox and IE

Well I have all my taxes turned off and deleted. For me in Firefox everything shows up correctly on the site. After adding something (in the admin panel) however, the price has changed from say 17 to 18. But again the price is still fine on the main page.

Now... someone else using Internet Explorer goes on the site. All of the products prices are wrong and appear to have that tax on them. If he makes an order in IE it actually uses the price with the tax.. whereas if I go and make the same order in firefox it'll be the proper price.

HELP??

Sorry for double posting but I tried to edit the thread and it didn't give me the option to. In the orders in the admin panel it'll show his product being 18 (taxes say 0) but i'll make the same order and it'll show 17 with taxes as 0 as well.

EDIT - Resolved this stupid thing myself.. im dumb lol. Anyways I guess all of the products were put in as USD... but when us canadian went on the site it automatically put us in as CAD and changed the prices. I added the currency box and figured the problem. Thanks guys