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	$78.36	10.398%	$86.5079	$86.51	$86.50	$86.50
Purchase #2	$7.35	8.472%	$7.9727	$7.97	$7.95	$8.00
Purchase #3	$178.42	4.219%	$185.9475	$185.95	$185.95	$185.90
Purchase #4	$241.42	11.661%	$269.572	$269.57	$269.55	$269.60
Purchase #5	$24.92	12.612%	$28.0629	$28.06	$28.05	$28.10
Purchase #6	$231.85	10.177%	$255.4454	$255.45	$255.45	$255.40
Purchase #7	$207.54	8.482%	$225.1435	$225.14	$225.15	$225.10
7 purchase totals =	$969.86		$1,058.6519	$1,058.65	$1,058.60	$1,058.60