Flat Sales Tax

[JuliaMeyers]

My accountant is telling me that I need to be collecting 10% sales tax on ALL website sales (this is the city/county/state sales tax rate of MY location).

I have selected all products to have sales tax applied but how do I have the flat % apply to all regions/states? I am testing a shipping address out of state and do not see that the sales tax is being applied. Is there another step that I need to take?