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	$221.79	9.608%	$243.0996	$243.10	$243.10	$243.10
Purchase #2	$6.98	8.427%	$7.5682	$7.57	$7.55	$7.60
Purchase #3	$195.28	11.282%	$217.3115	$217.31	$217.30	$217.30
Purchase #4	$90.43	10.835%	$100.2281	$100.23	$100.25	$100.20
Purchase #5	$144.92	6.624%	$154.5195	$154.52	$154.50	$154.50
Purchase #6	$249.27	5.734%	$263.5631	$263.56	$263.55	$263.60
Purchase #7	$160.91	6.755%	$171.7795	$171.78	$171.80	$171.80
7 purchase totals =	$1,069.58		$1,158.0695	$1,158.07	$1,158.05	$1,158.10