1. Use round to round to retain the two decimal places
2. Use ceil to round up and round to retain the two decimal places
3. Use sprintf to round and reserve the two decimal places, and automatically supplement the scene of the main application displaying amount.
4. High-precision functions do not round and reserve the two decimal places, and automatically add the following 0s.
5. High-precision functions round and reserve the two digits after the decimal point
6. Use number_format to round and reserve the two decimal places, and automatically add the following 0.
7. Use floor to round down and not round to retain the two decimal places