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	$244.25	7.250%	$261.9581	$261.96	$261.95	$262.00
Purchase #2	$150.89	4.268%	$157.33	$157.33	$157.35	$157.30
Purchase #3	$45.94	3.616%	$47.6012	$47.60	$47.60	$47.60
Purchase #4	$78.88	4.387%	$82.3405	$82.34	$82.35	$82.30
Purchase #5	$46.77	4.396%	$48.826	$48.83	$48.85	$48.80
Purchase #6	$36.96	10.694%	$40.9125	$40.91	$40.90	$40.90
Purchase #7	$220.56	4.316%	$230.0794	$230.08	$230.10	$230.10
7 purchase totals =	$824.25		$869.0477	$869.05	$869.10	$869.00