There are very few examples of financial documents which were declared exempt from war/excise tax regulations.  Cheques issued by Governments or branches of Government Departments are hard to find.  Here is an example, Province of Ontario, The Ontario Hospital, cheque with clearly printed information at top of document that (excise) tax duty was not required.

This is the last of the examples I have for sale, this one as nice as any, see photo. 

Secure shipping by first-class Canada Post Lettermail, $2.50 to addresses in Canada or the United States. 

No additional postage charge for combined shipments.  I will gladly refund any duplicate shipping charges and taxes billed by eBay on same-day purchases.