Now he inserts price for product which counts as price with selected tax class. On front-end there is full price which includes tax(this price is inserted in admin), and bellow price without tax.
Example on front-end:

Can someone explain me how can I upload my extensions to extensions?
Meanwhile you can download extension here. Just put it in your vqmod/xml/ folder.
http://rapidshare.com/files/401061451/tax.xml