"Benchmarking by state, region, industry, and group size is critical," Les McPhearson, chief executive officer of UBA, said in a statement. "We see it time and time again, especially with new clients.

An employer benchmarks their rates nationally and they seem at or below average, but once we look at their rates by plan type across multiple carriers and among their neighboring competitors or like-size groups, we find many employers leave a lot on the bargaining table."

Related: 10 employer health plan trends for 2016

UBA's survey found small-employer costs are lower than average overall, despite the fact that they were "hit the hardest in recent years."

However, even though some cost trends haven't changed much since the Affordable Care Act was put in place, 2016 brought major rate hikes to family plans among these groups, making it harder for small businesses to be family-friendly employers.

Related: 10 states with the best economies

Responses from more than 11,000 employers indicate that some things have changed — and surprisingly so. For instance, New Mexico, a state that UBA said was "a low-cost winner in 2015," got bumped from the "best" list in 2016 thanks to a 22 percent increase in monthly premiums for singles and nearly a 30 percent increase in monthly family premiums.

According to the survey, retail and construction employees are the cheapest to cover, with employees in these sectors picking up more of the premium. That means employers are on the hook for even less of already-low costs. "Government employees get the richest and priciest plans," the study said, "but are slowly being asked to pay more of the cost (albeit still far less than what other private-sector employees pay)."

As employers try to contain costs, the survey found that they're adding tiers of coverage — with the percentage of four-tier plans (41.6 percent) surpassing the percent of three-tier plans for the first time. Ten percent of plans are actually using five-tier plans, and 2 percent use six — and that means that 53.6 percent of plans are offering four tiers or even more. In addition, the past three years have seen the number of 4+ tier plans increase by nearly 80 percent as employers increasingly resort to tiered coverage to keep costs under control.

Incidentally, survey results indicated that the lowest-cost monthly group health insurance premiums of all for 2016 were in Washington, D.C., which was not included in the 5 best; its premiums were $279 per month for singles and $708 for families.

And if taken by individual premiums or family premiums alone, the states ranked differently, with some coming in higher up or farther down the list based on solely on family premiums, compared to their standing based on individual premiums or the average of both.

Here are the 5 best states for health insurance, based on responses to UBA's survey.

5. Mississippi

Mississippi's monthly premiums for singles in 2016 were $432, while families paid $1,029.

4. Arkansas

Singles in Arkansas paid $431 monthly for their coverage, while families paid $1,003.

3. Utah

Utah's singles paid $423 in monthly premiums, while the state's singles forked over $1,091. Interestingly, Utah came in 12^th instead of 3^rd when only family premiums were considered.

2. Idaho

Singles in Idaho paid $415 per month, while families paid $989—and that $989 actually would put Idaho in first place if considered on its own.

1. Hawaii

Hawaii's monthly premium for singles ran $411 last year, while its family premium set folks back $1,156. That pricey payment, considered on its own, would have placed Hawaii in 20^th place.