I know a while back they changed how they calculated the amount you saved by using PBS to get books.  I don't pay attention to it for the most part, but a couple of weeks ago I wrote down how much it said I'd saved - $2560.25.  Today I looked at it and I'd only saved $2490.81.  How come the downgrade?  And how do they calculate it these days?  I did give a bunch of credits back to PBS.  Would this be the difference?  Thanks. Pat

I think the calculation is based partly on postage (could be wrong, but I remember others saying that's how they calculate it). So, when the cost of postage went up, it might have changed your totals.

Sarah's probably right.  They adjusted it awhile back to take into account the postage spent (before it was just $4.50 x the # of books you've ordered).  Media mail went up 6 cents on Jan 22, so that's probably why the change. 

I don't think donating credits would have any impact on the total.