Do you really want the score,or is it OK to just have the vocal/piano arrangements of the main songs? If that is what you want, I've looked at this one, and it is fine:

CHICAGO
Movie Vocal Selections
Series: Piano/Vocal/Guitar Songbook
Publisher: Hal Leonard

$14.95 (US)
Inventory # HL 00313241
ISBN: 0634059556
UPC: 73999132410

Has All I Care About, And All That Jazz , Cell Block Tango ,Class , Funny Honey , I Can't Do It Alone,
I Move On, Mister Cellophane . Nowadays, Razzle Dazzle , Roxie , We Both Reached For The Gun , When You're Good To Mama--

If you need the full score(though I have know idea why you would) contact Samuel French, who provide such things for theater groups--