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	$119.52	11.615%	$133.4022	$133.40	$133.40	$133.40
Purchase #2	$243.44	4.549%	$254.5141	$254.51	$254.50	$254.50
Purchase #3	$191.69	4.326%	$199.9825	$199.98	$200.00	$200.00
Purchase #4	$18.80	9.793%	$20.6411	$20.64	$20.65	$20.60
Purchase #5	$92.40	12.860%	$104.2826	$104.28	$104.30	$104.30
Purchase #6	$217.32	9.444%	$237.8437	$237.84	$237.85	$237.80
Purchase #7	$60.60	9.224%	$66.1897	$66.19	$66.20	$66.20
7 purchase totals =	$943.77		$1,016.8559	$1,016.84	$1,016.90	$1,016.80