Visual Basic

Dim m_startDate As DateTime = New DateTime(2015, 9, 1, 0, 0, 0)
Dim m_stopDate As DateTime = New DateTime(2015, 9, 1, 23, 59, 59, 999)

Dim context As New hx5Context()
Dim pResult = _
(
    From oh In context.Order_History
    Where oh.OrderDate >= m_startDate _
    And oh.OrderDate <= m_stopDate _
    And oh.OrderStatus = "COMPLETED"
    Group By oh = New With
    {
        oh.SubTotal,
        oh.Shipping,
        oh.SalesTax,
        oh.GrandTotal
    } Into Group
    Select 
    {
        Group.Count(),
        Group.Sum(Function(m) m.SubTotal),
        Group.Sum(Function(m) m.Shipping),
        Group.Sum(Function(m) m.SalesTax),
        Group.Sum(Function(m) m.GrandTotal)
    }.FirstOrDefault()
)

pResult.Dump()