nginx send posts to proxy

upstream classic_upstream {
  fair;
  server 127.0.0.1:5500;
}

server {
  listen 80;

  server_name www.mywebsite.com website.com;

  root /data/classic/current/public;

  access_log /var/log/engineyard/nginx/classic/access.log main;

  error_log /var/log/engineyard/nginx/classic/error.log notice;

  include /etc/nginx/common/servers.conf;

  include /etc/nginx/servers/classic.rewrites;

  #include /etc/nginx/servers/classic/custom.locations.conf;


  location / {
    include /etc/nginx/common/proxy.conf;

    if ($request_method = POST) {
      proxy_pass http://classic_upstream;
      break;
    }

    if (!-f $request_filename) {
      proxy_pass http://classic_upstream;
      break;
    }
  }

  location = /500.html {
    root /data/classic/current/public;
  }
}