Do I have to post my hourly labor rate?

NH Hourly labor rate rules can be confusing. Rate rules and RSA 358-D are broken down in this article.

Not under NH or Federal law. The primary law that governs this area is RSA 358-D (Regulation of Motor Vehicle Repair Facilities). RSA 358-D requires that estimates and repair orders be provided to customers.  As you will see from the attached highlighted version, the law does not explicitly require that a shop post a labor rate. 
Rather, the shop must provide:
  1. “An estimated price for labor” (D:2); and
  2. “Shall prepare an invoice which itemizes….the number of hours, or portion thereof, of labor charged in performing the work and the retail cost of such labor.” (D:10).
Similarly, the shop must have a sign in the shop which lists the customer’s rights under the RSA. Please note that RSA 358 does not apply to a Motor Truck, motorcycles or motor-driven cycles.
The NH AG’s Consumer Sourcebook (applicable sections also attached) provides confusing guidance with one section advising that consumers find out whether they are being charged a flat rate or an hourly rate and another section providing that the RO should state “the hourly rate for the labor.” 
Franchised shops should check with their manufacturer which may have requirements on posting labor rates. If you do post a labor rate, be sure to qualify it by declaring that some jobs may be quoted on a flat rate basis regardless of how many hours spent on the job.
Per Saf-C 3208.02 – 3208.04 all inspections stations are required to have state specific signage including fees charged. It is important to note that if the inspection fee includes a separate fee for an OBD-II inspection, the inspection station shall break down the 2 fees on one sign. The inspection station signage rules (Saf-C 3208.02 – 3208.04)can be found here:

Helpful links with more information

RSA 358-D law

Consumer Sourcebook