Using if then else in rtf template

I have a client with a requirement to always show a tax code called 'CONSUMO' whether this tax was generated as tax line or not. In some cases they will generate such a tax line and in some cases they will not. The invoice however must always show the :CONSUMO' tax. If the tax line was generated the tax will generate at 5% and I have the data in my xml data file and the tags are there to use and this works well, but when they have not generated the tax I still have to show the tax as