Decimal Stamps-Postage Value Rounding?

For modern stamps that have a decimal number, does the USPS round up/down the value just like we all learned in elementary school? For example is a stamp with a face value of 10.1 cents worth 10 cents in postage and a stamp with a face value of 4.9 cents worth 5 cents in postage?

I suspect they add up all the postage on a piece exactly with no rounding and then see if the total is above or below the required amount.

What was the purpose of issuing stamps with decimals for the face value?

To pay an exact rate for non-regular first class mail.

The value of the stamp is as printed, no rounding done. Ten 10.1 stamps would total $1.01 in postage. Me, I use five 10.1 plus a 1/2 cent to make 51 cents.

PPG: Thank you for the explanation. What is non-regular first class mail?

There are various discounted rates of mail for certain organizations (non-profit) and preparation methods (sorted a certain way if there is enough volume [pieces] to qualify) as two examples. The were also discounts for other classes of mail if the mailing organization or person can qualify. A current example which does not produce fractions, is the discount on the postage for first class mail if paid by a meter imprint and not postage stamps. Today postage is 66 cents for a first class one ounce letter with stamps but only 63 cents if metered. The savings of three cents remains the same for just the first ounce, with no savings on additional ounces. Yet post cards remain at 51 cents no matter how paid, preprinted postal card, stamps or meter on a postcard.

Today there are still fractional (not round cents) postal rates, just no stamps issued for the rate. For example:




Currently EDDM-Retail is $0.198 (19.8 cents) for flats up to 3.3 ounces. If a stamp was issued for that mailing rate it would be 19.8 cents face value.

If one were to really study the various historic rates of postage fractional rates go back into the 1940s, and back to 1925 if counting half cent stamps as fractional (decimal) as while the value shown in 1/2 cent that is also .5 cent. The Liberty Series had a 1 1/4 (1.25) cent stamp. Up to then the not round number stamps were, 1/2, 1 1/2, 4 1/2, then 1 1/4 and 2 1/2 cents prior to as well as through the Prexies and then the Liberties. The transportation coils started the decimal point stamps which continued with other coils but did not spread to other formats.

The U. S. Domestic Postal Rates, 1872-XXXX (end date varies by edition)
by Henry W. Beecher & Anthony S. Wawrukiewicz discusses the fraction rates.

Edited for more information.

I believe that if you apply a total of 9.9c to a required 10c, they won't round it up and consider it underpaid. On the other hand, if you apply 20c worth of stamps on a 10c package/letter - they won't refund you.

Would they issue a Postage Due notice for the 0.1 cents unpaid? Would they give me 0.9 cents change if I gave the postman a penny?

I'd love to see if anyone has some examples on cover of modern postage dues for fractional amounts. I've seen earlier ones with 1/2 cent due, and the postman gives change by lightly tacking a second 1/2 cent postage due (uncancelled) to the envelope. But I don't know what they would do these days.

1/2 cent postage stamp, not postage due. The public can't use postage due stamps to mail letters.

Just in case, the "fractionals" that were issued in the Americana and the Transportation coils were NOT intended for the general public, but for specific mail classes like Nonprofit, presorted etc. There was no need to round these off because they were not used ( normally ) as a one piece item.
When collectors were able to use these we were supposed to put the correct amount on the envelope



Peter