I count the four highest exam scores (in other words, I drop the lowest exam, which could conceivably be the final). So, the students need to know their grades in advance of the final to decide if it's worth their while to prepare for and take the final.
Since the poorest students can't seem to figure out their grade on their own (big surprise there), I calculate all the grades, their final grade if they don't take the final and what grade would be necessary on the final in order to move them up to the next grade. It may seem like it's not my job, but I've found that doing it this way saves me far more time answering the "how do I figure out what I need on the final" questions.
However, within an hour of posting the grades, I got five (out of fifty students) emails asking how I calculated the grades. And this is after going over the calculations at least four times in class , with examples.
I'll just keep clicking my heels and repeating to myself, "there's no place like winter break...there's no place like winter break...).