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	$148.27	11.642%	$165.5316	$165.53	$165.55	$165.50
Purchase #2	$29.58	13.227%	$33.4925	$33.49	$33.50	$33.50
Purchase #3	$152.34	6.790%	$162.6839	$162.68	$162.70	$162.70
Purchase #4	$192.84	5.729%	$203.8878	$203.89	$203.90	$203.90
Purchase #5	$40.53	7.181%	$43.4405	$43.44	$43.45	$43.40
Purchase #6	$215.37	8.298%	$233.2414	$233.24	$233.25	$233.20
Purchase #7	$215.94	5.414%	$227.631	$227.63	$227.65	$227.60
7 purchase totals =	$994.87		$1,069.9087	$1,069.90	$1,070.00	$1,069.80