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	$95.95	8.132%	$103.7527	$103.75	$103.75	$103.80
Purchase #2	$15.98	9.656%	$17.523	$17.52	$17.50	$17.50
Purchase #3	$53.47	7.617%	$57.5428	$57.54	$57.55	$57.50
Purchase #4	$236.35	8.511%	$256.4657	$256.47	$256.45	$256.50
Purchase #5	$69.33	3.471%	$71.7364	$71.74	$71.75	$71.70
Purchase #6	$172.97	7.452%	$185.8597	$185.86	$185.85	$185.90
Purchase #7	$22.47	12.836%	$25.3542	$25.35	$25.35	$25.40
7 purchase totals =	$666.52		$718.2345	$718.23	$718.20	$718.30