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	$91.77	3.146%	$94.6571	$94.66	$94.65	$94.70
Purchase #2	$97.88	11.197%	$108.8396	$108.84	$108.85	$108.80
Purchase #3	$216.65	13.493%	$245.8826	$245.88	$245.90	$245.90
Purchase #4	$215.49	6.777%	$230.0938	$230.09	$230.10	$230.10
Purchase #5	$79.52	3.397%	$82.2213	$82.22	$82.20	$82.20
Purchase #6	$151.35	9.131%	$165.1698	$165.17	$165.15	$165.20
Purchase #7	$125.87	4.487%	$131.5178	$131.52	$131.50	$131.50
7 purchase totals =	$978.53		$1,058.3820	$1,058.38	$1,058.35	$1,058.40