A commonly used technique is to append a timestamp at the end of every request, like:

<link href="mywebsite.com/style.css

This way your browser shouldn't find any cached content for that exact url, thus downloading everytime the file.

Anyway you could probably think whether this is really what you want, or if you need some tweaking on the caching system in the web server.

For many cases, CTRL+F5 is enough in all modern browsers.

Additionally in Chrome, you can open the DevTools and then press and hold the refresh button until a menu pops up. From this menu select the 'empty cache and hard reload option'.

If this is experienced in a development environment, clearing the cache will be as easy as hitting Ctr+F5 (Command + Shift + R in OS X) and Hard reloading the assets, like @fibric suggested. In addition to his answer, I would add that Chrome has an option to disable the cache while the DevTools is opened. It can be found under DevTools settings - F2 when in DevTools or click the three dots on the top right side:

After that check Disable cache (while DevTools is open) under General:

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If you have this problem in production, you can append timestamp or a version number:

<link rel="stylesheet" type="text/css" href="style.css?4884491531235" />
<link rel="stylesheet" type="text/css" href="additional.css?v=1.23" />

Like @lorthirk mentioned, you should consider if this is what you really want. Breaking the cache would mean that you won't benefit at all from browser caching, which will disastrously affect the performance and load time of your app.

as for OS X, Command + Shift + R