When working with a complex struct data type in SQL that contains employee and sales data, how would you calculate the total sales made by all employees? The table is defined with batchId INT, performance ARRAY<STRUCT>, and insertDate TIMESTAMP. Here's a sample of the performance column data:

[
  { "employeeId": 1234, "sales": 10000 },
  { "employeeId": 3232, "sales": 30000 }
]

Given the following SQL to create the table sales:

create or replace table sales as
select 1 as batchId,
from_json('[{ "employeeId":1234,"sales" : 10000 },{ "employeeId":3232,"sales" : 30000 }]',
'ARRAY<STRUCT>') as performance,
current_timestamp() as insertDate
union all
select 2 as batchId,
from_json('[{ "employeeId":1235,"sales" : 10500 },{ "employeeId":3233,"sales" : 32000 }]',
'ARRAY<STRUCT>') as performance,
current_timestamp() as insertDate