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	$108.89	4.344%	$113.6202	$113.62	$113.60	$113.60
Purchase #2	$184.56	7.541%	$198.4777	$198.48	$198.50	$198.50
Purchase #3	$243.39	8.782%	$264.7645	$264.76	$264.75	$264.80
Purchase #4	$186.77	10.452%	$206.2912	$206.29	$206.30	$206.30
Purchase #5	$27.56	6.725%	$29.4134	$29.41	$29.40	$29.40
Purchase #6	$150.82	11.453%	$168.0934	$168.09	$168.10	$168.10
Purchase #7	$78.50	4.291%	$81.8684	$81.87	$81.85	$81.90
7 purchase totals =	$980.49		$1,062.5288	$1,062.52	$1,062.50	$1,062.60