The answer at this stage is no. You can’t add taxation to a clickfunnel order form at the time of this writing.
Clickfunnels is an American company. In the United States, you can roll taxation into all your products and sort it out later.
If you are Canadian for example, this will prove very challenging because different provinces have different taxation percentages.
I have asked Clickfunnels support, I have posted on the forum, I have contacted 3rd party companies and the answer is always the same. No!