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	$81.37	6.251%	$86.4564	$86.46	$86.45	$86.50
Purchase #2	$90.79	10.304%	$100.145	$100.15	$100.15	$100.10
Purchase #3	$93.93	8.765%	$102.163	$102.16	$102.15	$102.20
Purchase #4	$225.89	5.151%	$237.5256	$237.53	$237.55	$237.50
Purchase #5	$83.37	13.388%	$94.5316	$94.53	$94.55	$94.50
Purchase #6	$12.25	3.542%	$12.6839	$12.68	$12.70	$12.70
Purchase #7	$245.85	6.712%	$262.3515	$262.35	$262.35	$262.40
7 purchase totals =	$833.45		$895.8570	$895.86	$895.90	$895.90