Because of logistics, our system does two lipsticks at half off, which totals one lipstick free. The buy two get a 3rd half off is one deal. Then if you take advantage of the buy four get a fifth free, it just marks another one of the lipsticks half off so you get the 5th lipstick free. They are separate offers they don’t build on one another.
Another way to look at it would be:
If you were to buy five lipsticks full price it would cost $117.50. Having two marked at half price is the same as buying four and getting one free. $11.75+$11.75+$23.50+$23.50+$23.50= $94 which is the same as $23.50x4=94.