RESTful way to create multiple items in one request

I am working on a small client server program to collect orders. I want to do this in a "REST(ful) way".

What I want to do is:

Collect all orderlines (product and quantity) and send the complete order to the server

At the moment I see two options to do this:

1. Send each orderline to the server: POST qty and product_id

I actually don't want to do this because I want to limit the number of requests to the server so option 2:

2. Collect all the orderlines and send them to the server at once.

How should I implement option 2? a couple of ideas I have is: Wrap all orderlines in a JSON object and send this to the server or use an array to post the orderlines.

Is it a good idea or good practice to implement option 2, and if so how should I do it.

What is good practice?