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	$152.47	10.549%	$168.5541	$168.55	$168.55	$168.60
Purchase #2	$171.62	13.644%	$195.0358	$195.04	$195.05	$195.00
Purchase #3	$28.76	13.581%	$32.6659	$32.67	$32.65	$32.70
Purchase #4	$155.32	8.198%	$168.0531	$168.05	$168.05	$168.10
Purchase #5	$62.85	9.405%	$68.761	$68.76	$68.75	$68.80
Purchase #6	$60.43	3.627%	$62.6218	$62.62	$62.60	$62.60
Purchase #7	$55.67	6.268%	$59.1594	$59.16	$59.15	$59.20
7 purchase totals =	$687.12		$754.8511	$754.85	$754.80	$755.00