GROUP BY on a dependent field
The answer can be platform-specific. Although the results are the same, your performance might be very different.

I would suggest another approach, because it seems to clearly document the following intent: calculate some aggregates, then decorate them with another field(s). Here is an example:

WITH CustomerTotals AS(
SELECT CustomerID,
SUM(Amount) AS TotalAmount
FROM Orders
GROUP BY CustomerID
)
SELECT Customers.Name, CustomerTotals.TotalAmount
FROM  CustomerTotals JOIN Customers 
  ON CustomerTotals.CustomerID = Customers.CustomerID