Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$164.70	11.465%	$183.5829	$183.58	$183.60	$183.60
Purchase #2	$103.57	7.697%	$111.5418	$111.54	$111.55	$111.50
Purchase #3	$164.25	10.103%	$180.8442	$180.84	$180.85	$180.80
Purchase #4	$94.25	9.607%	$103.3046	$103.30	$103.30	$103.30
Purchase #5	$106.54	10.733%	$117.9749	$117.97	$117.95	$118.00
Purchase #6	$181.79	8.620%	$197.4603	$197.46	$197.45	$197.50
Purchase #7	$111.70	11.330%	$124.3556	$124.36	$124.35	$124.40
7 purchase totals =	$926.80		$1,019.0643	$1,019.05	$1,019.05	$1,019.10