How to calculate currency conversion for USA consumption tax (sales tax) reporting

The exchange rates that you are looking for is reported at this Department of Treasury website. Historical rates are available at a website linked to on this Department of Treasury page.

Resources from the U.S. Internal Revenue Service regarding how to apply these laws is found at the IRS website, which strictly speaking applies only to federal taxes and not to state and local sales taxes.

But many, if not most, states and local governments adopt the IRS rules for determining exchange rates by reference, and any state or local government that does not expressly provide how exchange rates are to be determined would very likely defer to the IRS guidance if a foreign taxpayer used it to make the exchange rate conversion.

The premise of the question is wrong: The U.S. has no authority or means to compel a company not under its jurisdiction to send it taxes taxes.

Furthermore, the U.S. government has no general "consumption tax." Many (but not all) states and municipalities have different "sales and use tax" rates, and different goods and services to which they apply.

At present the authority of those various jurisdictions to require collection of those taxes on companies located in other states – even within the U.S. – is limited.