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	$92.45	3.378%	$95.573	$95.57	$95.55	$95.60
Purchase #2	$28.69	8.260%	$31.0598	$31.06	$31.05	$31.10
Purchase #3	$232.39	6.497%	$247.4884	$247.49	$247.50	$247.50
Purchase #4	$141.89	12.466%	$159.578	$159.58	$159.60	$159.60
Purchase #5	$106.87	12.671%	$120.4115	$120.41	$120.40	$120.40
Purchase #6	$79.46	7.567%	$85.4727	$85.47	$85.45	$85.50
Purchase #7	$74.75	4.382%	$78.0255	$78.03	$78.05	$78.00
7 purchase totals =	$756.50		$817.6089	$817.61	$817.60	$817.70