When you have your Advanced Pricing Rules on a Ticket Type, you will see a quantity field at the top. This quantity box defines how many tickets there are available to sell in total. Within the pricing rules, you can define a quantity of tickets to sell in order to trigger the next pricing level. The quantity box for triggering the next pricing rule is option if you just want to trigger based on a date/time. However, if you want to ultimately limit the number of tickets sold in total, make sure to set the quantity at the top of that ticket type.
For example, let’s say you want to add pricing rules to your General Admission ticket. You would like to start selling at $10 for the first 50 tickets, then go to $15 until November 1st, then go to $20 until presale ends. However, you cannot sell more than 350 GA tickets, regardless of price. You would set the quantity box towards the top to 350 to tell the system to not sell more than 350. In the quantity box for the first pricing level, set that to 50 to tell the system to go to the next pricing level once those first 50 have sold.