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	$146.49	4.453%	$153.0132	$153.01	$153.00	$153.00
Purchase #2	$166.94	6.704%	$178.1317	$178.13	$178.15	$178.10
Purchase #3	$126.69	9.626%	$138.8852	$138.89	$138.90	$138.90
Purchase #4	$206.28	6.377%	$219.4345	$219.43	$219.45	$219.40
Purchase #5	$94.97	13.788%	$108.0645	$108.06	$108.05	$108.10
Purchase #6	$203.52	13.799%	$231.6037	$231.60	$231.60	$231.60
Purchase #7	$128.40	11.602%	$143.297	$143.30	$143.30	$143.30
7 purchase totals =	$1,073.29		$1,172.4298	$1,172.42	$1,172.45	$1,172.40