$ apt-get install nginx
Reading package lists... Done
Building dependency tree
Reading state information... Done
nginx is already the newest version.a
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

$ apt-cache  policy nginx
nginx:
  Installed: 1.2.1-2.2+wheezy3
  Candidate: 1.2.1-2.2+wheezy3
  Version table:
     1.6.2-2 0
        300 http://ftp.nl.debian.org/debian/ sid/main amd64 Packages
     1.6.2-1 0
        300 http://ftp.nl.debian.org/debian/ sid/main amd64 Packages
        400 http://ftp.nl.debian.org/debian/ testing/main amd64 Packages
     1.6.2-1~wheezy 0                                    ## <<-- WANT THIS ONE
        800 http://nginx.org/packages/debian/ wheezy/nginx amd64 Packages
 *** 1.2.1-2.2+wheezy3 0
        900 http://security.debian.org/ wheezy/updates/main amd64 Packages
        100 /var/lib/dpkg/status
     1.2.1-2.2+wheezy2 0
        900 http://ftp.nl.debian.org/debian/ wheezy/main amd64 Packages

deb http://nginx.org/packages/debian/ wheezy nginx
deb-src http://nginx.org/packages/debian/ wheezy nginx

# Install stable unless installed version is more recent.
Package: *
Pin: release o=Debian,a=stable
Pin-Priority: 900

# Allow to install testing, unless there is a stable release.
Package: *
Pin: release o=Debian,a=testing
Pin-Priority: 400

# Allow to install unstable, unless there is a stable release
Package: *
Pin: release o=Debian,a=unstable
Pin-Priority: 300

# Never install other packages from Debian
Package: *
Pin: release o=Debian
Pin-Priority: -1

# Install Nginx unless installed version is more recent.
Package: *
Pin: release o=nginx
Pin-Priority: 800