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	$92.80	4.342%	$96.8294	$96.83	$96.85	$96.80
Purchase #2	$154.75	9.116%	$168.857	$168.86	$168.85	$168.90
Purchase #3	$189.73	3.657%	$196.6684	$196.67	$196.65	$196.70
Purchase #4	$35.55	10.726%	$39.3631	$39.36	$39.35	$39.40
Purchase #5	$128.56	9.108%	$140.2692	$140.27	$140.25	$140.30
Purchase #6	$31.64	5.779%	$33.4685	$33.47	$33.45	$33.50
Purchase #7	$38.80	8.646%	$42.1546	$42.15	$42.15	$42.20
7 purchase totals =	$671.83		$717.6102	$717.61	$717.55	$717.80