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	$192.86	3.810%	$200.208	$200.21	$200.20	$200.20
Purchase #2	$52.94	3.407%	$54.7437	$54.74	$54.75	$54.70
Purchase #3	$18.87	8.679%	$20.5077	$20.51	$20.50	$20.50
Purchase #4	$80.52	8.811%	$87.6146	$87.61	$87.60	$87.60
Purchase #5	$146.51	6.872%	$156.5782	$156.58	$156.60	$156.60
Purchase #6	$23.35	9.341%	$25.5311	$25.53	$25.55	$25.50
Purchase #7	$196.89	6.823%	$210.3238	$210.32	$210.30	$210.30
7 purchase totals =	$711.94		$755.5071	$755.50	$755.50	$755.40