Here is CVS’s coupon policy.  I emailed them to see if they can send me an official document we can print and take to the store.  In the meantime, print this out because it comes directly from CVS so these are the rules.

• CVS/pharmacy will accept coupons printed from the Internet. They must have a legible barcode that scans at the register.
• If the coupon does not scan at the register, the cashier should politely inform you that we are unable to accept your coupon. We do not allow manual overrides at the register for coupons printed from the Internet.
• Our registers are set to allow 1 CVS coupon and 1 manufacturer coupon per item. However, the staff should be allowing customers to use Extra Bucks in combination with other CVS coupons since these are coupons you have “earned.” In addition, similarly they should be allowing the use of “offer at the register” coupons which would be an open offer of $3 off of $15 or a certain dollar amount off of a specific item. Since our registers are programmed to only accept 2 coupons (1 CVS, 1 manufacturer) per item if the number of coupons exceed the items purchased a member of management will need to assist the cashier in processing the coupons. I apologize in advance for any inconvenience this may cause.
• You can use coupons towards a clearance item but the coupon will be adjusted if it is more than the price of the item.
• The BOGO coupon allows you to purchase 2 items and get them both for free with a BOGO Free Sale. With the manufacturer’s coupons you can combine one with one CVS coupon. You will be responsible for any tax due.

Thanks Centsable Momma for sharing!