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	$60.53	3.561%	$62.6855	$62.69	$62.70	$62.70
Purchase #2	$202.66	4.173%	$211.117	$211.12	$211.10	$211.10
Purchase #3	$227.90	3.381%	$235.6053	$235.61	$235.60	$235.60
Purchase #4	$180.83	3.456%	$187.0795	$187.08	$187.10	$187.10
Purchase #5	$92.75	8.441%	$100.579	$100.58	$100.60	$100.60
Purchase #6	$59.43	11.449%	$66.2341	$66.23	$66.25	$66.20
Purchase #7	$30.95	3.443%	$32.0156	$32.02	$32.00	$32.00
7 purchase totals =	$855.05		$895.3160	$895.33	$895.35	$895.30