Total Cost reports inaccurate

Issue

In Truffle 5, the "migrate" command is much more verbose, and at the end of each migration a "Total cost" is reported, with a "final cost" at the end. These amounts are incorrect.

Steps to Reproduce

Use this repo and its readme for steps to reproduce. Use a relatively low value, like 500, for transactionsToRun in migration 3 (step 4), to avoid the other errors that repo helps illustrate.

Expected Behavior

The sum of migration "total cost" reports should equal the difference in account balance before - after the migration.

Actual Results

The reported "total cost" and "final cost" are much less than the amount the account balanced has decreased during the execution of that migration.

Environment

• Operating System: Windows 10 Pro
• Ethereum client: Ganache, tested with versions 1.3.0 and 2.0.0-beta2
• Truffle version (truffle version): 5.0.4
• node version (node --version): 9.3.0
• npm version (npm --version): 6.8.0