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	$74.25	10.456%	$82.0136	$82.01	$82.00	$82.00
Purchase #2	$154.60	4.493%	$161.5462	$161.55	$161.55	$161.50
Purchase #3	$190.66	5.366%	$200.8908	$200.89	$200.90	$200.90
Purchase #4	$229.28	5.762%	$242.4911	$242.49	$242.50	$242.50
Purchase #5	$77.58	10.732%	$85.9059	$85.91	$85.90	$85.90
Purchase #6	$149.84	7.492%	$161.066	$161.07	$161.05	$161.10
Purchase #7	$145.37	4.207%	$151.4857	$151.49	$151.50	$151.50
7 purchase totals =	$1,021.58		$1,085.3993	$1,085.41	$1,085.40	$1,085.40