Often referred to as Sales Taxes, VAT, and so forth. I have done the returns, and reviewed where need exists for self-assessments (mainly for the provincial sales tax programs - now being gradually replaced by VAT based HST programs).
The largest challenge in this topic resides in the area of 'real property'. It is largely a matter of interpretation to establish what is and what is not when it comes to the sales tax programs. However, it can have significant impact in industries touching construction.