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	$176.64	8.332%	$191.3576	$191.36	$191.35	$191.40
Purchase #2	$59.58	12.746%	$67.1741	$67.17	$67.15	$67.20
Purchase #3	$180.80	7.729%	$194.774	$194.77	$194.75	$194.80
Purchase #4	$125.75	13.158%	$142.2962	$142.30	$142.30	$142.30
Purchase #5	$226.83	3.800%	$235.4495	$235.45	$235.45	$235.40
Purchase #6	$140.57	5.866%	$148.8158	$148.82	$148.80	$148.80
Purchase #7	$131.57	11.415%	$146.5887	$146.59	$146.60	$146.60
7 purchase totals =	$1,041.74		$1,126.4559	$1,126.46	$1,126.40	$1,126.50