There is a ROUND function that you can use but the following explanation of how it works might surprise you.
If the digit to be rounded is 0 through 4 then round down to the lower number.
If the digit to be rounded is 6 through 9 then round up to the higher number.
If the digit is exactly 5 round up if the digit to the left is odd otherwise round down.
Hence in your case 12.075 is rounded up to 12.08 but 12.085 is rounded down to 12.08
Now it depends upon what you want. You can get up to all sorts of arithmetic tricks to produce variations on the above rules but I guess at the end of the day it's what C&E say about VAT calculations. It is a long time since I worked in the UK so I'm out of touch.
However there are a couple of basic principles that help to eliminate some of the rounding anomalies. First round each amount as early in the process as possible. Then when you add them up you are certain that your total is the true sum. Second, avoid using Double data type for these situations as it is impossible to store some numbers exactly in this type. Use Currency instead.
Thanks Rod, yes looked at round function before. Looks like I am going to have to get my head round righting a custom function for this one. Dont know if Access makes it any easier in later versions - its a pain not being able to drop curency boxes onto a report and add up correctly. VAT man wants either rounding down or up but must be consistent. Cheers.