Only the government charges: the port-of-entry application fee for a Canadian applicant, or Form I-129 fees if the employer petitions, plus TD fees for dependants, all published in the USCIS fee schedule. Everything else is a personal or employer cost.
A short list of government charges and a long list of everything else
The immigration charges for a Torbay TN applicant are few and are published in Form G-1055: the fee collected at the port of entry when a Canadian citizen applies there, or the Form I-129 filing fee and related surcharges if the employer petitions in advance, and the fees for dependants' TD applications. Premium processing is available for I-129 but not relevant to a port-of-entry application. The much longer list of costs that are not immigration fees includes a letter of good standing from the provincial CPA body, a credential evaluation if the degree is the sole basis, a U.S.
state CPA licence or reciprocity application if the employer wants one, professional fees for reviewing the file, moving costs, and the cost of establishing U.S. banking and housing. Employers frequently offer to reimburse some of these; the reimbursement is compensation and does not affect eligibility.
The accountant should ask the employer to state in writing which costs it covers, so that the offer letter and the household budget agree.