figure;
uicontrol('Style', 'Slider', 'Position', [10, 10, 200,20], ...
'SliderStep', [1/29, 0.1], ...
'Min', 10, 'Max', 300, 'Value', 10, ...
'Callback', 'disp(get(gcbo, ''Value''))')
The range goes from 10 to 300, which is a distance of 290. To get a stepsize of 10, the SliderStep must be 10/290, or 1/29. You should expect rounding errors, so fix the value in the callback:
uicontrol('Style', 'Slider', 'Position', [10, 10, 200,20], ...
'SliderStep', [1/29, 0.1], ...
'Min', 10, 'Max', 300, 'Value', 10, ...
'Callback', mySliderCB);
function mySliderCB(SliderH, EventData)
Value = round(get(SliderH, 'Value'));
set(SliderH, 'Value', Value);
...
