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	$107.94	5.612%	$113.9976	$114.00	$114.00	$114.00
Purchase #2	$169.71	12.484%	$190.8966	$190.90	$190.90	$190.90
Purchase #3	$49.37	10.232%	$54.4215	$54.42	$54.40	$54.40
Purchase #4	$89.33	3.547%	$92.4985	$92.50	$92.50	$92.50
Purchase #5	$41.68	8.286%	$45.1336	$45.13	$45.15	$45.10
Purchase #6	$105.52	11.367%	$117.5145	$117.51	$117.50	$117.50
Purchase #7	$150.81	11.420%	$168.0325	$168.03	$168.05	$168.00
7 purchase totals =	$714.36		$782.4948	$782.49	$782.50	$782.40