JSFiddle - React, Tailwind, and code Playground

HTML

<html>
    <body>
        <input type="button" id="priceUp" value="add" />
        <input type="text" id="priceInput" value="0" />
    </body>
</html>

JavaScript

$("#priceUp").click(function(){ 
    var xyz = parseFloat($("#priceInput").val());
    xyz += 0.1;
    var oneDecimalVar = Math.round(xyz*10)/10;
    $("#priceInput").val(oneDecimalVar);
});