Shell Programming and Scripting

Is there a method to see how much data is put on a tape? Or to check and see the size of what you are tarring to tape? I have a script that checks a partition and user's directories and excludes anything under a home/test directory and writes that to a text file, then I call tar and using that text file tell it to copy everything to tape, but how can i test to see how much, size, was copied to tape? I've done the du -ks /home/ and that tells me total size, but how do i do I see size minus all those /test/ directories? I do all this at the command prompt, no program, just my scripts. I'm sure there's a better way to backup , but at this point, it works and I'm looking into a better way to back up data other than tarring to tape each time a full partition (or maybe not, the tapes only cover 4 Gb of data, i don't know if i'm getting everything unless i get an error message and am around to see it, I do log everything that's tarred, but that doesn't tell me the size and then a sum of everything).

oops, forgot to say, working in Unix, Solaris 2.5.1 on a Sparc 5.