Price adjustment

Hi,
i have a little problem with pricing manager, cause we sell in italy, we need to add 22% VAT on every invoice. We want to sell a package at 15 € (Euro) tax included, but if we put € 12,29 it returns a price with VAT of € 14,99, if we put € 12,30 it returns a price with VAT of € 15,01. Any trick?
Other question (probably an invoicing plugin issue), it’s not possible to add 2 not mandatory fields ( Company Name and VAT number) in the invoice instead of the “validate VAT number to exclude tax”?. We can’t sell without tax….
Thanks

Sandro