Why would you think sales tax is one such case? Is it really that difficult to back out how you don't have that 8-10% to spend? Does it really justify confidently telling someone they don't know their tax rate because they included it?
(FWIW, the "employer's" side should be included too but can be misleading in conventional contexts because you'd have to restate your pretax income to include that as well, when it is generally not understood to. But it's fairly characterized as part of your burden.)
Also not all of sales tax really falls on me. Some % falls on the provider of the goods in the form of lower prices. It depends on the price elasticity of the product in question. Taking this into account would only further complicate the question.
[1] I'm a very precise record keeper of my income taxes now after I screwed something up years ago which cost me $$$. I keep everything in a github repository. It's pretty awesome actually. Highly recommended!
That's true for all taxes, but not a reason to arbitrarily clip (only) one out and tell someone he's wrong for including it.
Also ya, I left out sales tax (I don't have any precise records on my yearly sales tax expenditures. I suppose I could estimate). I also left out the employer side of FICA which is really a tax I'm paying. I also left out the % of my rent that goes to pay my landlord's property tax. I also left out corporate taxes I'm responsible for as an owner of stock in various public companies.
Truly calculating the total taxes that fall on me as an individual is probably impossible at some level. So I included the taxes that people commonly refer to when talking about "paying their taxes."