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	$156.77	9.759%	$172.0692	$172.07	$172.05	$172.10
Purchase #2	$20.59	11.322%	$22.9212	$22.92	$22.90	$22.90
Purchase #3	$73.69	11.434%	$82.1157	$82.12	$82.10	$82.10
Purchase #4	$123.70	10.449%	$136.6254	$136.63	$136.65	$136.60
Purchase #5	$76.78	9.240%	$83.8745	$83.87	$83.85	$83.90
Purchase #6	$91.30	3.283%	$94.2974	$94.30	$94.30	$94.30
Purchase #7	$156.64	8.385%	$169.7743	$169.77	$169.75	$169.80
7 purchase totals =	$699.47		$761.6777	$761.68	$761.60	$761.70