Added this thread to an existing feature request for customizable step sizes, thank you for posting this! And as always, to anyone else reading this, please feel free to add your +1's 
For display purposes in the meantime (this doesn't actually help any use cases since we can't grab the value of the HTML component to use in a query, for example), you could use an HTML input type="number" component with a customizable step size and you could add CSS to make it look more like a Retool component.
