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	$86.58	3.528%	$89.6345	$89.63	$89.65	$89.60
Purchase #2	$6.82	7.439%	$7.3273	$7.33	$7.35	$7.30
Purchase #3	$194.74	7.493%	$209.3319	$209.33	$209.35	$209.30
Purchase #4	$231.83	6.710%	$247.3858	$247.39	$247.40	$247.40
Purchase #5	$191.78	4.153%	$199.7446	$199.74	$199.75	$199.70
Purchase #6	$169.91	8.196%	$183.8358	$183.84	$183.85	$183.80
Purchase #7	$88.82	11.625%	$99.1453	$99.15	$99.15	$99.10
7 purchase totals =	$970.48		$1,036.4052	$1,036.41	$1,036.50	$1,036.20