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	$174.60	13.239%	$197.7153	$197.72	$197.70	$197.70
Purchase #2	$41.32	11.162%	$45.9321	$45.93	$45.95	$45.90
Purchase #3	$61.89	11.734%	$69.1522	$69.15	$69.15	$69.20
Purchase #4	$218.56	10.868%	$242.3131	$242.31	$242.30	$242.30
Purchase #5	$49.85	8.826%	$54.2498	$54.25	$54.25	$54.20
Purchase #6	$103.59	3.149%	$106.852	$106.85	$106.85	$106.90
Purchase #7	$9.50	10.760%	$10.5222	$10.52	$10.50	$10.50
7 purchase totals =	$659.31		$726.7367	$726.73	$726.70	$726.70