well you could take a purely mechanical approach, i.e. place divi say 1 minute b4 the off being in proportion (OR BETTER) to the win divi, presuming youre betting on the tote, (I did see a guide about this somewhere) but personally I wouldn't bet at less than $1.30.
If the same approach is used for win betting then of course top flux with a bookie (some don't even charge a commission for this) would see your returns 5-10% better. Some will even accept a "NO BET LESS THAN" stipulation.