I use Commsec & would probably average 50 to 80 transactions per year & had the same problem. I trialed a product called "Topshare Portfolio Manager" a couple of years ago, then bought it & now tax time is a breeze, one of the best investments I ever made. (cant remember how much but around $200 I think?)
Some here will use various forms of excel spreadsheets, others will spend a lot of time doing it the manual way & others would have more sophisticated software. Hope you get a few positive responses, & what 123enen stated is absolutely correct;)