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	$223.64	6.346%	$237.8322	$237.83	$237.85	$237.80
Purchase #2	$53.47	5.633%	$56.482	$56.48	$56.50	$56.50
Purchase #3	$224.75	5.541%	$237.2034	$237.20	$237.20	$237.20
Purchase #4	$58.73	7.165%	$62.938	$62.94	$62.95	$62.90
Purchase #5	$28.93	7.209%	$31.0156	$31.02	$31.00	$31.00
Purchase #6	$42.66	6.617%	$45.4828	$45.48	$45.50	$45.50
Purchase #7	$54.94	11.841%	$61.4454	$61.45	$61.45	$61.40
7 purchase totals =	$687.12		$732.3994	$732.40	$732.45	$732.30