Variable postage and package?

[Guest]

Apologies if this has a very simple answer.

 

I want to be able to add variable posting and package charges.

 

I.e. if the customer orders under ?10 worth of goods they pay ?2 postage and packaging.

 

If there order is over ?10, postage and packaging is free.

 

Is this possible by the admin system, or do I need to install a custom module / script.

 

Thanks in advance.