This is done on Fedora 10. File paths may change depending on what install package or location you install to.

On Fedora 10 the path is LSMB_ROOT=/usr/share/ledgersmb

To maintain an orginal untouched set of templates you should always copy the demo templates away to a new folder and select this new folder as your default templates in the LedgerSMB admin control panel(see picture below).

Copy Demo Templates
cp -rv $LSMB_ROOT/templates/demo $LSMB_ROOT/templates/custom
if you do this as root you need to change the ownership to the apache user.

Enable Web Server Write Permissions to Custom Templates
On Fedora / Redhat
chown -Rv apache.apache $LSMB_ROOT/templates/custom
On Ubuntu / Debian
chown -Rv www-data.www-data $LSMB_ROOT/templates/custom

Configure Custom Templates

Changing Invoice to Tax Invoice
vi $LSMB_ROOT/templates/custom/invoice.tex
find \textbf{I N V O I C E}
and change it to
\textbf{TAX I N V O I C E}

vi $LSMB_ROOT/templates/custom/invoice.html
Find this
<th colspan=3>
<h4>I N V O I C E</h4>
</th>
and change it to
<th colspan=3>
<h4>TAX I N V O I C E</h4>
</th>

Note:
You can make these changes from the LedgerSMB Application Login at “System ==> Latex Templates ==> Invoice” and “System ==> HTML Templates ==> Invoice” respectively. However you would have to do the steps of copying the demo templates to a new directory and then setting the new templates as the “Use Templates” option in the Admin control panel.