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	$196.84	13.319%	$223.0571	$223.06	$223.05	$223.10
Purchase #2	$117.54	10.854%	$130.2978	$130.30	$130.30	$130.30
Purchase #3	$215.65	4.606%	$225.5828	$225.58	$225.60	$225.60
Purchase #4	$225.61	13.331%	$255.6861	$255.69	$255.70	$255.70
Purchase #5	$202.49	6.597%	$215.8483	$215.85	$215.85	$215.80
Purchase #6	$12.66	9.691%	$13.8869	$13.89	$13.90	$13.90
Purchase #7	$130.73	8.845%	$142.2931	$142.29	$142.30	$142.30
7 purchase totals =	$1,101.52		$1,206.6521	$1,206.66	$1,206.70	$1,206.70