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	$105.53	11.130%	$117.2755	$117.28	$117.30	$117.30
Purchase #2	$12.41	9.834%	$13.6304	$13.63	$13.65	$13.60
Purchase #3	$228.38	7.374%	$245.2207	$245.22	$245.20	$245.20
Purchase #4	$196.86	7.150%	$210.9355	$210.94	$210.95	$210.90
Purchase #5	$207.65	12.820%	$234.2707	$234.27	$234.25	$234.30
Purchase #6	$130.26	11.708%	$145.5108	$145.51	$145.50	$145.50
Purchase #7	$74.89	4.244%	$78.0683	$78.07	$78.05	$78.10
7 purchase totals =	$955.98		$1,044.9119	$1,044.92	$1,044.90	$1,044.90