[('A', '', Decimal('21.0000000000'), 1330, datetime.datetime(2012, 5, 14, 0,
    0)), ('A', '', Decimal('4.0000000000'), 1330, datetime.datetime(2012, 6,
    8, 0, 0)), ('AA', 'C', Decimal('31.0000000000'), 1330, datetime.
    datetime(2012, 5, 31, 0, 0)), ('B', '', Decimal('7.0000000000'), 1330,
    datetime.datetime(2012, 5, 24, 0, 0)), ('B', '', Decimal(
    '31.0000000000'), 1330, datetime.datetime(2012, 6, 4, 0, 0))]
Python - Group by and sum a list of tuples