I believe that, before the euro came in, stamps of the Bundesrepublik gave denominations esentially in Pfennigs, even stamps worth more than a Mark, so that a stamp with “150” on it would have been for 1.5 Marks. or 150 Pfennigs. This post-euro usage seems to be continuing that idea.
Thanks, everyone. I had asked for some German Christmas items to be sent from home and just wanted to make sure I sent enough to cover both purchase and shipping. My folks back home aren’t that well off…