How does the QGIS construct class intervals?

I'm using graduated style of a point layer to assign a colour ramp to symbols (squares). I assigned manual values to class intervals specifying classes to be:

0.60 - 0.80
0.80 - 1.00

That is, in entering class bounds for a lower class I used 0.600000 as lower value and 0.800000 as upper. And then 0.800000 as lower for next class.

How are then the class intervals constructed in such case? Are they:

(0.60 - 0.80)
[0.80 - 1.00)

Or:

(0.60 - 0.80]
(0.80 - 1.00]
...