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	$192.28	12.114%	$215.5728	$215.57	$215.55	$215.60
Purchase #2	$147.38	10.265%	$162.5086	$162.51	$162.50	$162.50
Purchase #3	$100.85	10.821%	$111.763	$111.76	$111.75	$111.80
Purchase #4	$114.52	12.574%	$128.9197	$128.92	$128.90	$128.90
Purchase #5	$213.95	4.682%	$223.9671	$223.97	$223.95	$224.00
Purchase #6	$133.55	6.736%	$142.5459	$142.55	$142.55	$142.50
Purchase #7	$151.61	11.283%	$168.7162	$168.72	$168.70	$168.70
7 purchase totals =	$1,054.14		$1,153.9933	$1,154.00	$1,153.90	$1,154.00