Jīntiān jiù dào zhèr ba.

今天就到这儿吧。

Let's call it a day.

Notes:

今天(jīntiān): today

就(jiù): just

到这儿(dào zhèr): stop here

吧(ba): a particle word shows the whole setence is a suggestion

Example:

A：今天就到这儿吧。

     Jīntiān jiù dào zhèr ba. 

     Let's call it a day.

B：老师再见。

     Lǎoshī zàijiàn.

     Bye, teacher.