If I set the zoom of a tab to 120%, then when opening new tabs, Visual Studio 2012 should open them with a 120% zoom factor and not 100% (the default).
But when reopening, Visual Studio the Zoom Percentage should be preserved (120%).
Is there is any way to solve the issue?
If you are simply zooming so the text in your editor is bigger, then why not just increase the font size?
Open TOOLS -> OPTIONS, under the 'Environment' tab select 'Fonts and Colors', and change the font size to whatever you want.
--edit--
As @Anovative pointed out in his comment and answer below, there is now a way to set default zoom within Visual Studio 2013 (and subsequent versions I'd assume).