When they installed the system years ago, I asked the installer how to defeat the system. This works. Before the store opens, get a ladder and redirect the AC vents to aim right at the sensors. Heat triggers the sensors. In the winter, direct the vents away from the sensors. Be sure all the fly fans are turned on the entrance doors full bore.
Train your courtesy clerks on registers. Let them know that the expectation is that when the Que Visions spikes up, they hop on a register, and when it goes back down, they go back to bagging. The que vision is always followed then, and sure you will have a few less baggers but overall front end efficiency is much improved.
Also have head clerks directing customers into the till with the shortest line. Customers appreciate it and it solves the problem of customers only using some of the open tills.
Sorry for the triple reply, I keep thinking of things I have my checkers do. Have your checkers stand at the end of their lane when they do not have a customer and wave customers into their lane when they come by ready to check out. This also improves the evenness of customers in each line.