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	$212.70	7.515%	$228.6844	$228.68	$228.70	$228.70
Purchase #2	$174.68	6.173%	$185.463	$185.46	$185.45	$185.50
Purchase #3	$99.38	7.520%	$106.8534	$106.85	$106.85	$106.90
Purchase #4	$48.98	8.781%	$53.2809	$53.28	$53.30	$53.30
Purchase #5	$129.58	9.707%	$142.1583	$142.16	$142.15	$142.20
Purchase #6	$102.89	8.794%	$111.9381	$111.94	$111.95	$111.90
Purchase #7	$100.48	5.186%	$105.6909	$105.69	$105.70	$105.70
7 purchase totals =	$868.69		$934.0690	$934.06	$934.10	$934.20