usa – Is there an easy way to calculate the total cost of tolls for a trip within the United States?

If you know your route, you could use CostofTolls.com  CostToDrive.com  Tollsmart.com (paywall, $2 minimum) or their free mobile app:

Sample:

CALIFORNIA

17-Mile Drive Toll: $9.25 Location: Scenic drive through Pebble
Beach, CA Operator: Pebble Beach Corporation

Golden Gate Bridge Toll: $6.00 (Southbound ONLY) Location: Spans
San Francisco Bay connecting San Francisco to Marin County, CA
Operator: Golden Gate Bridge, Highway & Transportation District

Riverside Freeway (SR-91) Toll: Variable Location: An east-west
freeway in Southern California linking Orange and Riverside counties
Operator: Orange County Transportation Authority (OCTA)

Eastern Transportation Corridor Toll: $3.50 (East Branch) $3.25
(West Branch) Location: Orange County, CA Operator: Foothill/Eastern
Transportation Corridor Agency

South Bay Expressway Toll: Variable Location: Beginning at Otay
Mesa, provides access to/from Mexico and across San Diego Operator:
South Bay Expressway, L.P.

The Antioch Bridge Toll: $5.00 (Northbound ONLY) Location: Spans
the San Joaquin River linking Antioch, CA with Sacramento County, CA
Operator: Bay Area Toll Authority Metropolitan Transportation
Commission

The Benicia-Martinez Bridge Toll: $5.00 (Northbound ONLY) Location:
Spans the Carquinez Strait linking Benicia, CA to Martinez, CA
Operator: Bay Area Toll Authority Metropolitan Transportation
Commission

you get the idea.