Ya know, I was just thinking on this more, and calculating exp is the least of the annoyaces for tracking stuff. Magic Items and if they have been identified or not, and tracking anything but gold pieces are the bigger PITA for me personally.
I have taken to writing magic items on index cards for tracking who has what, but I have dumped the whole identify thing in favor of a spellcraft chance to ID it right away, or deduct 100gp from the total of the adventure for identify purposes.
As for coppers, silver, electrum, etc, all of those are converted to GP. Anything less than 1gp in value is dropped (or if it's low level, its 1gp total).
But EXP has become easy now that I use that spreadsheet to calculate.