While some practices or objectives may vary by the context the team is in, this is not one of them.  When more than one or two tests are not complete it is an indication that there are one or more of several problems present. These include:

• Different people are doing coding and testing. In Scrum these should not be separate roles. But if you do have people doing coding and testing it is critical that they do this working together or at least with high collaboration.
• The sprints are done as mini-waterfall cycles. This delays feedback. At a minimum have those writing the code help those testing the code finish before starting new work when testers get behind.
• Testing takes too long because of a lack of automated tests. Automate the tests.

These can usually be solved by using Acceptance Driven Development Using Behavior-Driven Development. ATDD/BDD does not have to be a dramatic adoption, but can be started in phase. See How to start with ATDD using BDD.

Other practices that will help are:

• Automated testing
• Continuous integration
• Small stories
• People writing code and people testing code working together