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	$100.44	13.464%	$113.9632	$113.96	$113.95	$114.00
Purchase #2	$101.83	9.132%	$111.1291	$111.13	$111.15	$111.10
Purchase #3	$153.53	8.395%	$166.4188	$166.42	$166.40	$166.40
Purchase #4	$190.82	4.449%	$199.3096	$199.31	$199.30	$199.30
Purchase #5	$143.49	7.383%	$154.0839	$154.08	$154.10	$154.10
Purchase #6	$113.38	4.325%	$118.2837	$118.28	$118.30	$118.30
Purchase #7	$32.63	7.751%	$35.1592	$35.16	$35.15	$35.20
7 purchase totals =	$836.12		$898.3475	$898.34	$898.35	$898.40