CVS coupon order

CVS has by far, the best employees that are the most coupon friendly of any store around! Andrea at my CVS helped me out this morning with my coupons and she taught me something new. Imagine that, a cashier teaching a customer a coupon trick. ONLY at CVS would that happen! Here was my deal:
Ban deodorant 2.99 with 2 ECB back. I also had a $1/1 coupon. I decided to get 2 of the deodorants even though I would only get the ECB back on one(it was limit 1). I knew after the $4ECB and two of the $1/1 coupons, my order total would be -.02. I always try to at lease owe a little bit of money and not have a negative balance and I was not sure how that would go over in the system. Andrea told me that if I used my ECB first, and the coupons last, the coupons would overlap(pay some towards) on the tax, where as the ECBs would not. So, for future reference, at CVS, if you are going to have a negative balance on your order, use the ECB first and the manufacturer coupons last.
Here is what my receipt looked like:
So, I ended up using $4ECB and paying .40 and getting back $2ECB for 2 ban deodorants. Thank you for your help, Andrea!

~All Thanks to God!~