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	$174.45	5.473%	$183.9976	$184.00	$184.00	$184.00
Purchase #2	$9.31	8.451%	$10.0968	$10.10	$10.10	$10.10
Purchase #3	$244.56	6.685%	$260.9088	$260.91	$260.90	$260.90
Purchase #4	$41.44	8.468%	$44.9491	$44.95	$44.95	$44.90
Purchase #5	$226.49	12.590%	$255.0051	$255.01	$255.00	$255.00
Purchase #6	$94.76	9.140%	$103.4211	$103.42	$103.40	$103.40
Purchase #7	$212.81	4.708%	$222.8291	$222.83	$222.85	$222.80
7 purchase totals =	$1,003.82		$1,081.2076	$1,081.22	$1,081.20	$1,081.10