HABU. I copied this from a forum concerning your particular Canadian dime.
I'm assuming that you have a dime from Canada with the fish (mackerel). These were made in such huge numbers, and being a very popular one-year-only type, that they were saved in huge numbers. Unless it is in uncirculated condition ($4 and up depending on how nice), it's only worth the silver in it. Except that for only a single coin, a dealer isn't going to bother.
There is also the problem of which type it is. Before 1967 (and after 1919) Canadian silver coins were 80% silver and 20% copper. During 1967, Canada lowered the silver content for dimes and quarters to 50%. So, both 80% and 50% exists for 1967. The 80% dime has about $2 worth of silver, the 50%, $1.30. It is almost impossible to tell them apart because, unlike other coins where the composition has changed and the newer coins weigh less, the difference in weight between these two dimes is so tiny that most scales can't pick it up. That's why when you go to sell 1967 dimes, buyers won't pay more than the lower price.