Mysql SUM with case statement

SELECT 
    SUM(
        CASE 
           WHEN cumulative = 1 
           THEN percent 
           ELSE 0 
        END) 
FROM phppos_items_taxes;

Given the above statement does this do the following:

mysql> select * FROM phppos_items_taxes;
+---------+-----------+---------+------------+
| item_id | name      | percent | cumulative |
+---------+-----------+---------+------------+
|       1 | Tax 1     |    8.00 |          0 |
|       1 | Tax 2     |   10.00 |          1 |
|       3 | Sales Tax |    8.00 |          0 |
|       4 | Tax 1     |   20.00 |          0 |
|       4 | Tax 2     |   20.00 |          0 |
+---------+-----------+---------+------------+

Does this SUM up percent for each row that cumulative = 1. If cumulative != 1 then 0 is summed.