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	$132.57	12.169%	$148.7024	$148.70	$148.70	$148.70
Purchase #2	$40.55	13.145%	$45.8803	$45.88	$45.90	$45.90
Purchase #3	$167.67	3.636%	$173.7665	$173.77	$173.75	$173.80
Purchase #4	$122.91	11.604%	$137.1725	$137.17	$137.15	$137.20
Purchase #5	$187.40	4.377%	$195.6025	$195.60	$195.60	$195.60
Purchase #6	$89.47	4.268%	$93.2886	$93.29	$93.30	$93.30
Purchase #7	$152.33	10.852%	$168.8609	$168.86	$168.85	$168.90
7 purchase totals =	$892.90		$963.2737	$963.27	$963.25	$963.40