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	$200.86	5.818%	$212.546	$212.55	$212.55	$212.50
Purchase #2	$8.76	4.549%	$9.1585	$9.16	$9.15	$9.20
Purchase #3	$186.74	9.627%	$204.7175	$204.72	$204.70	$204.70
Purchase #4	$127.79	12.509%	$143.7753	$143.78	$143.80	$143.80
Purchase #5	$205.94	4.633%	$215.4812	$215.48	$215.50	$215.50
Purchase #6	$203.92	9.559%	$223.4127	$223.41	$223.40	$223.40
Purchase #7	$70.50	3.239%	$72.7835	$72.78	$72.80	$72.80
7 purchase totals =	$1,004.51		$1,081.8747	$1,081.88	$1,081.90	$1,081.90