Hey there @EndlessDream
If you hold the CTRL key on your keyboard while slowly dragging the slider with your mouse, you should be able to jump with a 1 step increment value. Holding the Alt Key will also give you other jumps values settings.
This works inside many plugins, as well as holding the Shift key for some Plugins, always give a try to those key strokes when a Plugin doesn't allow to manually enter the value.
Hope this helps