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	$125.87	5.623%	$132.9477	$132.95	$132.95	$132.90
Purchase #2	$6.89	13.321%	$7.8078	$7.81	$7.80	$7.80
Purchase #3	$215.40	10.333%	$237.6573	$237.66	$237.65	$237.70
Purchase #4	$56.71	9.613%	$62.1615	$62.16	$62.15	$62.20
Purchase #5	$109.48	7.683%	$117.8913	$117.89	$117.90	$117.90
Purchase #6	$80.46	6.263%	$85.4992	$85.50	$85.50	$85.50
Purchase #7	$153.71	9.788%	$168.7551	$168.76	$168.75	$168.80
7 purchase totals =	$748.52		$812.7199	$812.73	$812.70	$812.80