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	$192.50	5.494%	$203.076	$203.08	$203.10	$203.10
Purchase #2	$54.98	4.410%	$57.4046	$57.40	$57.40	$57.40
Purchase #3	$101.40	10.361%	$111.9061	$111.91	$111.90	$111.90
Purchase #4	$47.52	6.778%	$50.7409	$50.74	$50.75	$50.70
Purchase #5	$202.91	7.203%	$217.5256	$217.53	$217.55	$217.50
Purchase #6	$19.35	11.436%	$21.5629	$21.56	$21.55	$21.60
Purchase #7	$89.43	12.105%	$100.2555	$100.26	$100.25	$100.30
7 purchase totals =	$708.09		$762.4716	$762.48	$762.50	$762.50