The government cost differs by route: a port-of-entry application involves the fees CBP collects at the time, while an employer petition on Form I-129 involves the USCIS filing fees. Current amounts are published in the USCIS fee schedule, Form G-1055.
The filing fee is the small number in this budget
Quoting a dollar figure for TN is unhelpful because the schedule changes; the G-1055 is the only source worth relying on, and it should be checked on the day. The costs that actually move a budget sit elsewhere. Rowan may need a credential evaluation if any part of his diploma was earned outside Canada, Mexico or the United States.
He will likely pay for an adviser to read the offer letter against the Hotel Manager rule before he travels, which is far cheaper than a refusal. Certified translations are charged per document. If the employer files a petition, it decides whether to pay for premium processing.
Dependants in TD carry their own application costs. The one thing to settle in writing is which of these the resort group will pay, because employers frequently cover the petition and nothing else.