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	$167.99	9.320%	$183.6467	$183.65	$183.65	$183.60
Purchase #2	$79.53	4.178%	$82.8528	$82.85	$82.85	$82.90
Purchase #3	$214.85	8.134%	$232.3259	$232.33	$232.35	$232.30
Purchase #4	$95.42	13.630%	$108.4257	$108.43	$108.45	$108.40
Purchase #5	$191.75	9.568%	$210.0966	$210.10	$210.10	$210.10
Purchase #6	$149.39	10.522%	$165.1088	$165.11	$165.10	$165.10
Purchase #7	$111.76	10.791%	$123.82	$123.82	$123.80	$123.80
7 purchase totals =	$1,010.69		$1,106.2765	$1,106.29	$1,106.30	$1,106.20