I started answering your question, but realized that it was much less trivial than I thought when I started playing with the OAuth 2.0 API . I think it would be a lot easier if you could publish your Google spreadsheet, but I doubt it makes sense with sales data.
The reason this is not trivial is part of authentication. The OAuth ASP below can probably be used with some work, but I noticed that it uses session variables and some other ASP objects, so you will need to make a lot of settings.
In this light, here is my original answer if it helps.
There is a google spreadsheet API: https://developers.google.com/google-apps/spreadsheets/#adding_a_list_row
The OAuth 2.0 link to which the document table belongs is out of date. You can play with OAuth requests here , which should help you get started.
API functions are called with GET / POST requests with XML, which you can call using the XMLHTTP object.
First specify the Microsoft XML link in the Excel project (Tools-> Links-> Microsoft XML, v6.0)
In your VBA, you essentially use the following to send XML requests:
Dim x as MSXML2.XMLHTTP Set x = New MSXML2.XMLHTTP x.Open "POST", "http://example.com/", False x.Send "<xmldata></xmldata>"
You should be able to adapt this OAuth 2.0 ASP library for your VBA code.
This is an ASP example on how to use this OAuth library; again, since ASP and VBA use VBScript syntax, perhaps it would be adaptable.