The fundraise round will close for certain at the company's offering deadline. 

However, almost always, a successful fundraise closes earlier (although it must be open for at least 21 days).  Additionally, some companies may do a "rolling close" after 21 days have passed and their minimum fundraising target is reached.

When a round closes earlier, you will receive a five-day notice before the closing date via email and a 7-day countdown will be on the visible on the fundraise page.