I'd roll it into a sub and pass in the mode etc:

sub calcDigest {
    my ($fileName, $mode, $opt_u, %family) = @_;
    my $inFile;

    if (!open ($inFile, '<', $fileName)) {
        print STDERR "$0 : cannot open file \"$fileName\"\n";
        return 0;
    }
    binmode $inFile;
    my $dObj = Digest::SHA->new ($mode);
    my $digest;
    if ($family{"sha$mode"}) {
        $dObj->addfile ($inFile);
        $digest = $dObj->digest;
        my $ps = unpack ("B*", $digest);
        while (length ($ps) < 160) {$ps = "0$ps";}
        print "sha$mode($fileName)= $ps\n";
        seek (FILE, 0, 0);
    }
    if ($family{"sha${mode}_hex"}) {
        $dObj->addfile ($inFile);
        $digest = lc ($dObj->hexdigest);
        if ($opt_u) {$digest = uc ($digest);}
        print "sha${mode}_hex($fileName)= $digest\n";
        seek (FILE, 0, 0);
    }
    if ($family{"sha${mode}_b64"}) {
        $dObj->addfile ($inFile);
        $digest = $dObj->b64digest;
        while (length ($digest) % 4) {$digest .= '=';}
        print "sha${mode}_b64($fileName)= $digest\n";
    }
    close ($inFile);
}
[download]

Note that the original code printed sha1($fileName)= for the sha256 case in the $do_256 branch. I assumed that was copy and paste error and 'corrected' it.

Update: type globs removed per jwkrahn's reply (doh!).