28%= 9 cents
29%= 10 cents
30%= 11 cents
Remember the Postal System is a Service
First I believe the correct percentage you were looking for was %23. Also, the cost of doing business will go down, admittedly for some more than others.
As for the U.S.P.S., I assume they get tax breaks as is, (I may be wrong about that), I'm sure they can cut spending since I used to sell them $100s of dollars of pizza, and we as postal customers picked up the tab!
So I'll give ya a penny or 2 on a stamp, by the way I thought it would be a VERY GOOD idea if I posted a link to the bill since I didn't see one anywhere else on the forum, so here it is. Its pretty straight forward considering what it is.
Thanks for the link to HR25 - we sometimes forget to post it assuming that everyone knows how to find it (which of course isn't true).
Actually, it's quite likely that postal rates wouldn't change at all since prices for the many things the USPS buys (including the $100s of $ of pizza before the FairTax tax) will decline and then be raised back by the sales tax to about where they are now.