Examine source code of Price Rounder

{
  "manifest_version": 2,
  "name": "Price Rounder",
  "version": "1.0",
  "description": "Rounds price tags to better represent what they actually cost (49 -> 50 | 99 -> 100).",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "pricerounder@justbanana.org",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ]
}