When use tabs in advanced search a slider will get a unique id per tab. The id of the slider is composed as ‘slider_price_’.$term_id; where $term_id is the id of the category.

You can also found the id of the slider by  using browser inspect element and select the actual slider .

Screenshot

Once you have the id’s of the slider you must make the change into control.js around line 2090 (after this line  setTimeout(function(){ $(‘.tooltip’).fadeOut(“fast”);},10000); )

and add a code similar with this one
jQuery("#your_slider_id").slider({
step: 1000
})
Replace your_slider_id with your id and 1000 with your new step.
Also please note that if you are using minified versions of the js files you will have to recreated the minified version of the control.js file
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For price slider shortcode use below code:
jQuery("#slider_price_sh").slider({ step: 1000 })

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If use multi currency widget you must add below code before new code added for slider steps:

if( isNaN(my_custom_curr_coef) ) {

my_custom_curr_coef=1;
};

Screenshot