[ESMA 70-872942901-38 MiFID II MiFIR market structures Q&A, Q&A 4.11]

Yes, periodic auction trading systems are subject to the tick size regime defined under Article 49 of MiFID II and further specified under CDR (EU) 2017/588. Therefore, market operators and investment firms operating such trading systems need to ensure that orders are submitted and that transactions are executed at a price that is in line with the mandatory tick size regime. For periodic auction systems that do not benefit from a reference price waiver, this prohibits the execution of transactions at a price that corresponds to the mid-point in cases where the spread consists of an uneven number of ticks.