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	$180.54	8.598%	$196.0628	$196.06	$196.05	$196.10
Purchase #2	$194.31	5.617%	$205.2244	$205.22	$205.20	$205.20
Purchase #3	$86.47	3.733%	$89.6979	$89.70	$89.70	$89.70
Purchase #4	$103.70	13.491%	$117.6902	$117.69	$117.70	$117.70
Purchase #5	$12.27	12.660%	$13.8234	$13.82	$13.80	$13.80
Purchase #6	$100.40	7.205%	$107.6338	$107.63	$107.65	$107.60
Purchase #7	$33.37	8.566%	$36.2285	$36.23	$36.25	$36.20
7 purchase totals =	$711.06		$766.3610	$766.35	$766.35	$766.30