Using Standard Memo Line Items in AR and would like to create some of these Items with no Tax calcu

Hi,

We are using Standard Memo Line Items in AR  and would like to create some of these Items with no Tax calcuated using eTax?  Our current current customers have been defined with a Bill-To Province(or State) which the eTax engine uses to generate the appropriate tax for the province or state jurisdiction. That is automaitcally  applied to all  predefined Standard Memo lines on our AR invoice. However, we would like to define some items where the Tax isn't calculated or exempt...Any suggestions, documentation, examples?

Thanks,

John