Hello John. I've just uploaded 2.80 for final small fixes. While doing that I added a small feature that may help on creating "%50 off for second item" promotions.
I added "Toggle" feature to "Update Program Setting" action. If you choose "Update Type" as "Toggle" and enter "0,1" as Setting Value this action will switch [SettingName] between 0 and 1 on each call.
For a "2nd Pizza %50 off" promotion we'll create three actions and three rules. One action will toggle PIZZAPROMO value between 0 and 1, Second action will apply Price Tag to ticket line and the third action will disable PIZZAPROMO setting. As you know we can use less actions by using variables.
First "Line added to Ticket" rule will apply price tag to last ticket item if PIZZAPROMO = 1 and the second "Line added to Ticket" rule will call toggle action. Third "Ticket Closed" rule will set "PIZZAPROMO" setting to 0.
I think this small change will add lots of possibilities.
