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	$79.52	7.577%	$85.5452	$85.55	$85.55	$85.50
Purchase #2	$16.36	5.620%	$17.2794	$17.28	$17.30	$17.30
Purchase #3	$64.83	4.650%	$67.8446	$67.84	$67.85	$67.80
Purchase #4	$69.98	11.657%	$78.1376	$78.14	$78.15	$78.10
Purchase #5	$219.70	6.320%	$233.585	$233.59	$233.60	$233.60
Purchase #6	$139.90	5.855%	$148.0911	$148.09	$148.10	$148.10
Purchase #7	$103.52	8.297%	$112.1091	$112.11	$112.10	$112.10
7 purchase totals =	$693.81		$742.5920	$742.60	$742.65	$742.50