I need to often be reminded of how to calculate a percentage.  The context here is that I want a progress bar in one of my programs.

(Progress So Far / Total Progress Units) * 100 = %
or
(Net Amount / Gross Amount) * 100 = %

eg. (12 steps / 30 steps) * 100 = 40%   ie. 12 steps of 30 is 40% progress
eg. ($8 / $10) * 100 = 80%              ie. $8 of $10 is 80%

To setup your store to use SSL (Secure Socket Layer) you will first need an SSL certificate. Many hosting companies will either provide (or can offer) "Shared SSL" or the option to buy a "Dedicated SSL" certificate.

Shared SSL means that your store will run using two domains your master domain name and shared secure domain which may be used by other customers of your hosting company.
Dedicated SSL means that you will have your own SSL certificate which enable you to run your store on one domain using http and https.

This happened to a m8s website in VirtueMart 1.1.3. The issue here was that although all the prices lost their float/decimal and were rounded up to the nearest integer...  

At first we thought this was due to installing a Virtuemart UK Credit Card Payment Module (vm-ukcreditcard). A lot of forums were suggesting to change the number_format to convert any number to a currency or two decimal places. Another suggestion was to alter the main virtuemart database table (jos_vm_prodcut_price)...

Don't do any of these things!

After modifying tax rates and ensuring these were all the same, we also found that this was due to a country not being specified under the Store configuration within VirtueMart.

As the instructions to installing a new payment module in Virtuemart for Joomla! I've done this video showing how I apply it to my demo site.