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	$187.91	4.763%	$196.8602	$196.86	$196.85	$196.90
Purchase #2	$130.52	12.385%	$146.6849	$146.68	$146.70	$146.70
Purchase #3	$79.99	4.147%	$83.3072	$83.31	$83.30	$83.30
Purchase #4	$181.76	8.295%	$196.837	$196.84	$196.85	$196.80
Purchase #5	$139.35	11.815%	$155.8142	$155.81	$155.80	$155.80
Purchase #6	$148.62	3.868%	$154.3686	$154.37	$154.35	$154.40
Purchase #7	$69.72	10.118%	$76.7743	$76.77	$76.75	$76.80
7 purchase totals =	$937.87		$1,010.6464	$1,010.64	$1,010.60	$1,010.70