Dishwasher recess size

I'm building a house, my builder has left 600mm Width x 900mm High x 600mm Deep recess for the dishwasher on their plan. Standard 60CM dishwasher from Bosch/ASCO etc I've seen has width of @598mm on their specs. I'm not sure what width recess should be left. Is 10 to 20mm more than dishwasher dimesion on suppplier spec sheet ok or will it look bad (because of extra gap)?

Any ideas?
I'm keeping 605mm Wide x 600mm Deep x 900mm High.

I think I'll buy 60cm Built-in Under-Counter Dishwasher. I hope 605mm recess width can fit 60cm dishwasher (spec sheet for most DW says 598mm width of DW).

Any opinions?
Generally, when you build a house the kitchen guy asks you to supply the specifications for the dishwasher you are buying before kitchen is built.

I'm told by the cabinet makers, if dishwasher is 600mm then for under the counter built in dishwasher the gap of the recess required is exactly 600mm - no more.
You will generally find that the width of dishwashers and ovens for that matter which are marketed as 600mm wide are ~598.

Just installed a new dishwaher in a new kitchen, the fit is tight and the difference in the gap between the d/w and the cabinetry and the gap of the vertical lines in the between the other doors is negligable and would not be picked up by a normal eye.