Wah How to use "So" to give explanation

You may know how to use So in many way 
Wah How to use "So + Adjective / Adverb + That"
Wah How to use "So do I / Neither do I" 

And if you want to explain why you are doing something, you can use...

• I need to get to the book store so that I can buy new arrival books.
• I'm going to the bank so I can change my foreign currency.
• Shall we go someplace quieter so we can talk in private.
• Let's go to the theater early so that we can get good seats.  
• Let's hurry so that we can catch the train.
• Lisa got a part-time job so that she could study at college.
• The money was round so that it could roll from place to place.