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	$57.91	6.548%	$61.7019	$61.70	$61.70	$61.70
Purchase #2	$104.72	6.550%	$111.5792	$111.58	$111.60	$111.60
Purchase #3	$237.46	4.709%	$248.642	$248.64	$248.65	$248.60
Purchase #4	$133.66	5.460%	$140.9578	$140.96	$140.95	$141.00
Purchase #5	$145.42	13.291%	$164.7478	$164.75	$164.75	$164.70
Purchase #6	$202.92	10.520%	$224.2672	$224.27	$224.25	$224.30
Purchase #7	$69.27	4.671%	$72.5056	$72.51	$72.50	$72.50
7 purchase totals =	$951.36		$1,024.4015	$1,024.41	$1,024.40	$1,024.40