checkIgnore example

function ignoreRemoteUncaught(isUncaught, args, payload) {
  try {
    var filename = payload.data.body.trace.frames[0].filename;
    if (isUncaught && !filename.match(/^https?:\/\/www\.mycompany\.com/)) {
      // Ignore uncaught errors that are not from www.mycompany.com.
      return true;
    }
  } catch (e) {
    // Most likely there was no filename or the frame doesn't exist.
  }
  return false;
}

Rollbar.configure({checkIgnore: ignoreRemoteUncaught});

// or...

_rollbarConfig({
  // ...
  checkIgnore: ignoreRemoteUncaught
});

UPDATE: You no longer need to use the data key. The filename should be found like this:
var filename = payload.body.trace.frames[0].filename;

https://gist.github.com/and-megan/d234875541e88f4a8185adecb4b79734