I've declared dutiable alcohol returning from Canada by car & been dismissed by Customs several times, esp. Niagara Falls. Land borders in the prairies tend to be stricter, as inspectors have time on their hands. At airports I have cleared Customs duty-free bag in hand, & the taxes have never been collected. Also, the others are right about the ? on the form.
If you're unlucky enough to get a strict inspector, combined duty & Internal Revenue tax is a buck or three a bottle.
In conclusion, collecting $10 tax from you would distract Customs & INS from the more important mission of catching cocaine dealers & terrorists.