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	$49.65	8.531%	$53.8856	$53.89	$53.90	$53.90
Purchase #2	$242.72	5.185%	$255.305	$255.31	$255.30	$255.30
Purchase #3	$195.48	12.677%	$220.261	$220.26	$220.25	$220.30
Purchase #4	$171.38	12.295%	$192.4512	$192.45	$192.45	$192.50
Purchase #5	$99.90	13.361%	$113.2476	$113.25	$113.25	$113.20
Purchase #6	$152.47	10.547%	$168.551	$168.55	$168.55	$168.60
Purchase #7	$170.57	12.465%	$191.8316	$191.83	$191.85	$191.80
7 purchase totals =	$1,082.17		$1,195.5330	$1,195.54	$1,195.55	$1,195.60