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	$219.64	12.743%	$247.6287	$247.63	$247.65	$247.60
Purchase #2	$32.80	6.109%	$34.8038	$34.80	$34.80	$34.80
Purchase #3	$180.90	8.381%	$196.0612	$196.06	$196.05	$196.10
Purchase #4	$200.65	6.383%	$213.4575	$213.46	$213.45	$213.50
Purchase #5	$162.71	11.532%	$181.4737	$181.47	$181.45	$181.50
Purchase #6	$69.92	6.246%	$74.2872	$74.29	$74.30	$74.30
Purchase #7	$59.55	10.468%	$65.7837	$65.78	$65.80	$65.80
7 purchase totals =	$926.17		$1,013.4958	$1,013.49	$1,013.50	$1,013.60