If you would like to use this for adding arrows/other icons to a button for example then you could use css pseudo-elements?
If it's really a background-image for the whole button, I tend to incorporate the spacing into the image, and just use 
background-position: right 0;
But if I have to add for example a designed arrow to a button, I tend to have this html:
<a href="[url]" class="read-more">Read more</a>
And tend to do the following with CSS:
.read-more{
    position: relative;
    padding: 6px 15px 6px 35px;//to create space on the right
    font-size: 13px;
    font-family: Arial;
}
.read-more:after{
    content: '';
    display: block;
    width: 10px;
    height: 15px;
    background-image: url('../images/btn-white-arrow-right.png');
    position: absolute;
    right: 12px;
    top: 10px;
}
By using the :after selector, I add a element using CSS just to contain this small icon. You could do the same by just adding a span or <i> element inside the a-element. But I think this is a cleaner way of adding icons to buttons and it is cross-browser supported.
you can check out the fiddle here:
http://codepen.io/anon/pen/PNzYzZ