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	$165.98	6.448%	$176.6824	$176.68	$176.70	$176.70
Purchase #2	$215.72	8.232%	$233.4781	$233.48	$233.50	$233.50
Purchase #3	$243.95	10.456%	$269.4574	$269.46	$269.45	$269.50
Purchase #4	$86.26	6.574%	$91.9307	$91.93	$91.95	$91.90
Purchase #5	$55.71	10.547%	$61.5857	$61.59	$61.60	$61.60
Purchase #6	$91.44	6.614%	$97.4878	$97.49	$97.50	$97.50
Purchase #7	$151.54	8.531%	$164.4679	$164.47	$164.45	$164.50
7 purchase totals =	$1,010.60		$1,095.0900	$1,095.10	$1,095.15	$1,095.20