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	$190.30	3.261%	$196.5057	$196.51	$196.50	$196.50
Purchase #2	$17.65	12.111%	$19.7876	$19.79	$19.80	$19.80
Purchase #3	$68.56	3.584%	$71.0172	$71.02	$71.00	$71.00
Purchase #4	$125.75	5.513%	$132.6826	$132.68	$132.70	$132.70
Purchase #5	$107.52	8.401%	$116.5528	$116.55	$116.55	$116.60
Purchase #6	$112.72	9.363%	$123.274	$123.27	$123.25	$123.30
Purchase #7	$81.48	8.549%	$88.4457	$88.45	$88.45	$88.40
7 purchase totals =	$703.98		$748.2656	$748.27	$748.25	$748.30