They will use the old time-tested weapon of the incentive to try to move some inventory after a weak June, saleswise. GM's sales declined 12 percent last month, and Ford's fell 8 percent, while both Chrysler and the companies' Japanese rivals saw upward movement. GM plans to announce some major deal-of-the-century type numbers next week, but Ford may not match these outright, as they still want to focus on profit. Among the speculated reasons for June's soft sales: several incentive offers had just ended without any beginning anew, and the typically brisk April and May period that usually feeds into a slight decline didn't show quick recovery. Neither company sees elevated gas prices as a contributing factor.