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	$52.52	10.294%	$57.9264	$57.93	$57.95	$57.90
Purchase #2	$138.89	4.196%	$144.7178	$144.72	$144.70	$144.70
Purchase #3	$176.31	7.512%	$189.5544	$189.55	$189.55	$189.60
Purchase #4	$246.39	13.595%	$279.8867	$279.89	$279.90	$279.90
Purchase #5	$136.45	13.549%	$154.9376	$154.94	$154.95	$154.90
Purchase #6	$100.65	4.547%	$105.2266	$105.23	$105.25	$105.20
Purchase #7	$150.64	8.386%	$163.2727	$163.27	$163.25	$163.30
7 purchase totals =	$1,001.85		$1,095.5222	$1,095.53	$1,095.55	$1,095.50