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	$43.70	6.107%	$46.3688	$46.37	$46.35	$46.40
Purchase #2	$203.62	5.679%	$215.1836	$215.18	$215.20	$215.20
Purchase #3	$205.73	13.509%	$233.5221	$233.52	$233.50	$233.50
Purchase #4	$201.72	10.671%	$223.2455	$223.25	$223.25	$223.20
Purchase #5	$49.62	6.856%	$53.0219	$53.02	$53.00	$53.00
Purchase #6	$198.67	12.705%	$223.911	$223.91	$223.90	$223.90
Purchase #7	$111.34	5.318%	$117.2611	$117.26	$117.25	$117.30
7 purchase totals =	$1,014.40		$1,112.5140	$1,112.51	$1,112.45	$1,112.50