Does your office or in your State do they charge sales tax on blueprints or copies of plan sets?

Speaking to a friend, he told me their firm was visited by the TAX MAN and told that when they sell or charge someone for plan sets or sheets that MINNESOTA requires Sales Tax be charged.

Anyone else from Minnesota or other States deal with this?
Does your firm charge for plan sets?
Do you charge or collect sales tax?

Seems like quite a bit of redtape.  How does your firm charge or deal with this.  This is the first I ever heard of this, yet my friend was told this changed 2-years ago.  The TAX MAN may go back through their records and charge them.  Of all the firms I have worked for, I do not recall ever seeing Sales Tax being charged.

Would it not be better to just estimate plan set printing costs and include a contract item Misc. project expences "Lump Sum" or just include the costs into the project?