You must declare if you are carrying in excess of $10k in cash or cash equivalents (bearer bonds, cheques payable to "cash", negotiable securities, gold bullion, etc. Anything that isn't registered to you specifically). However, there is no duty on bringing in cash. The rules are actually in place to prevent money laundering. It turns out it is quite common for immigrants to carry actual cash with them, so CBSA is used to people declaring they are carrying $20-30k in cash with them.
There is no tax due on cash or equivalents that you bring into Canada. If you bring $100k in with you they might ask you to prove the source of the funds, but if you carried that much cash I'd wonder for your sanity.
Good luck!