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	$58.72	4.501%	$61.363	$61.36	$61.35	$61.40
Purchase #2	$103.59	7.811%	$111.6814	$111.68	$111.70	$111.70
Purchase #3	$233.76	7.740%	$251.853	$251.85	$251.85	$251.90
Purchase #4	$13.28	6.482%	$14.1408	$14.14	$14.15	$14.10
Purchase #5	$137.40	10.763%	$152.1884	$152.19	$152.20	$152.20
Purchase #6	$228.95	5.803%	$242.236	$242.24	$242.25	$242.20
Purchase #7	$47.89	12.548%	$53.8992	$53.90	$53.90	$53.90
7 purchase totals =	$823.59		$887.3618	$887.36	$887.40	$887.40