What round ticket for an airline to buy if i want to use multiple Tourist visas

Hello, So i would like to go to China on a tourist type. Which is only for 30 days. But i know i can extend it 2 times in china for another 30 days. To get the tourist type you need a return flight. Can i for example purchase a round trip that leaves February 15th and returns May 14th? And i will tell them i plan to extend my tourist type when i am in china. Or must i have a return flight within 30 days?