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	$222.52	5.381%	$234.4938	$234.49	$234.50	$234.50
Purchase #2	$95.60	5.121%	$100.4957	$100.50	$100.50	$100.50
Purchase #3	$96.79	8.496%	$105.0133	$105.01	$105.00	$105.00
Purchase #4	$106.93	4.601%	$111.8498	$111.85	$111.85	$111.80
Purchase #5	$207.65	4.384%	$216.7534	$216.75	$216.75	$216.80
Purchase #6	$229.74	3.674%	$238.1806	$238.18	$238.20	$238.20
Purchase #7	$89.45	4.384%	$93.3715	$93.37	$93.35	$93.40
7 purchase totals =	$1,048.68		$1,100.1581	$1,100.15	$1,100.15	$1,100.20