Giant Tiger has emailed me their coupon policy! Here it is:
Thank you for taking the time to e-mail us.
Please note that if it is a valid manufacturers’ coupon with the manufacturer’s information available (i.e includes instructions to retailers, barcode, expiry date etc), we do accept coupons.
As for your second question, our system is not currently linked to the item and Manufacturer’s coupons are treated as tender. For this reason, the full amount of the coupon would be applied.
Internet coupons are particularly troublesome as most do not have the required elements for stores to accept.
We do not allow more then one coupon per item (stacking).
Please note that the store owner will have the final word on which coupon his store is accepting.