Tax rules vary by state, county, and city, and many states tax products and services differently. Setting one flat rate on the whole invoice is rarely correct.
Glo Invoice supports per-line-item taxability (taxable vs non-taxable) and granular tax jurisdictions. Set your defaults once in the business profile and it applies them everywhere.
For multi-state work, you can override the rate per invoice. Sales tax reports break out by jurisdiction at year end.