We understand the need of such feature and consider having it. As you can see there is a long discussion stating the pros and cons, and the reason why there is no justify alignment in Telerik Reporting yet.
For now please try using a third party tool to post process the report documents or use our editors - AJAX RadEditor
or Silverlight RadRichTextBox
- which can also produce documents and apply justify on the text elements.
New HTML5/JS REPORT VIEWER with MOBILE AND TOUCH SUPPORT available in Telerik Reporting Q3 2013! Get the new Reporting version from your account or download a trial.