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	$118.36	7.541%	$127.2855	$127.29	$127.30	$127.30
Purchase #2	$51.45	3.684%	$53.3454	$53.35	$53.35	$53.30
Purchase #3	$130.97	4.325%	$136.6345	$136.63	$136.65	$136.60
Purchase #4	$110.25	10.805%	$122.1625	$122.16	$122.15	$122.20
Purchase #5	$96.82	3.522%	$100.23	$100.23	$100.25	$100.20
Purchase #6	$58.51	6.804%	$62.491	$62.49	$62.50	$62.50
Purchase #7	$87.45	6.125%	$92.8063	$92.81	$92.80	$92.80
7 purchase totals =	$653.81		$694.9552	$694.96	$695.00	$694.90