the question about round, truncate

Dear all.

I have a question about round, truncate.

I want to   fix the data like 3-digit decimal after being rounded on 4-digit decimal.

Ex. Geometryformat(‘linestring((54.11238742 22.023498293, 35.128937123 94.129837123))’,-1);

     -------> #######(‘linestring((54.112 22.023, 35.129 94.130))’,-1);

What should I do?

I want to use the round, truncate command.

I’m sorry my English is poor.

Best regards and thanks in advance.

Kevin.