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	$176.89	12.711%	$199.3745	$199.37	$199.35	$199.40
Purchase #2	$217.84	5.804%	$230.4834	$230.48	$230.50	$230.50
Purchase #3	$60.30	6.510%	$64.2255	$64.23	$64.25	$64.20
Purchase #4	$118.78	9.684%	$130.2827	$130.28	$130.30	$130.30
Purchase #5	$212.85	5.531%	$224.6227	$224.62	$224.60	$224.60
Purchase #6	$28.91	12.738%	$32.5926	$32.59	$32.60	$32.60
Purchase #7	$140.28	9.680%	$153.8591	$153.86	$153.85	$153.90
7 purchase totals =	$955.85		$1,035.4405	$1,035.43	$1,035.45	$1,035.50