Hmm this calls for some Spreasheet-FU...
http://www.tentonhammer.com/node/226951/page/3 is a decent starter for min compressionhttp://eve.battleclinic.com/ore_compression_calculator.php#compression if you need to compress a certain mineral the compress tab should help you find the right bpo for it.
As a lazy approximation, 425mm Railgun Is to compress all the trit you need works pretty well. You end up needing to bring a bit extra zydrine, nocxium, and mexallon, but you don't end up with too much surplus. Worst offender is isogen but even that's not too bad.
In addition to the above http://www.fuzzwork.co.uk/compression/ is a handy guide I often refer to as well. My corp specialises in mineral compression modules so mail or convo me in-game if you want some more information.
Think I'm okay, but I could use somebody with experience to check my plan for anything horribly wrong -- http://eve-fail.blogspot.com/2012/10/mineral-compression-beta-plan.html
Give this a tryhttp://icculus.org/~riot/compression-calc.html