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	$45.57	6.551%	$48.5553	$48.56	$48.55	$48.60
Purchase #2	$217.71	3.763%	$225.9024	$225.90	$225.90	$225.90
Purchase #3	$119.77	6.181%	$127.173	$127.17	$127.15	$127.20
Purchase #4	$132.43	10.165%	$145.8915	$145.89	$145.90	$145.90
Purchase #5	$112.32	11.701%	$125.4626	$125.46	$125.45	$125.50
Purchase #6	$157.72	8.732%	$171.4921	$171.49	$171.50	$171.50
Purchase #7	$230.90	3.152%	$238.178	$238.18	$238.20	$238.20
7 purchase totals =	$1,016.42		$1,082.6549	$1,082.65	$1,082.65	$1,082.80