I see that I set the calculation on UPS rate rather than USPS rate... my mistake, however when corrected it still does not work.
Maybe the best way is just to add a flat rate $1.30 markup to the standard first-class/parcel post rate that is returned by the shipping quote. That would cover the slight difference in Priority mail cost, plus the $.80 delivery confirmation fee.
If you have other suggestions, I'd love to hear...!?