my $BYTES = 0;

$sftp->put(               
    "testfile",           
    "testfile",           
    cleanup  => 1,        
    callback => sub {        
                          
        my ( $sftp, $data, $offset, $size ) = @_; 
        print $offset ." of ". $size ." bytes copied\n";
last_bytes($offset);                                                            
    } );     

print "\nTransferred $BYTES bytes\n";
                                                                                      
sub last_bytes {
    my ($bytes) = @_;
    $BYTES = $bytes;
}