To answer myself (I got response from customer service):
Any order comes with 75 bucks of credit (presumably excluding inexpensive items such as shirts). Even if the order contains 10 suits, still, 75 bucks, not 750.
Buttom line is: buy each item in separate order (unless you have very good reason, e.g. the recent 30% off orders of $700 or more).
Hope it helps.