For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Application:ERP:GNUHealth:5.0/openSUSE_Tumbleweed/Application:ERP:GNUHealth:5.0.repo
zypper refresh
zypper install trytond_account_invoice
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Application:ERP:GNUHealth:5.0/16.0/Application:ERP:GNUHealth:5.0.repo
zypper refresh
zypper install trytond_account_invoice
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Application:ERP:GNUHealth:5.0/15.6/Application:ERP:GNUHealth:5.0.repo
zypper refresh
zypper install trytond_account_invoice