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	$64.62	7.532%	$69.4872	$69.49	$69.50	$69.50
Purchase #2	$83.69	8.155%	$90.5149	$90.51	$90.50	$90.50
Purchase #3	$7.68	7.714%	$8.2724	$8.27	$8.25	$8.30
Purchase #4	$72.33	8.235%	$78.2864	$78.29	$78.30	$78.30
Purchase #5	$129.99	8.279%	$140.7519	$140.75	$140.75	$140.80
Purchase #6	$234.75	8.855%	$255.5371	$255.54	$255.55	$255.50
Purchase #7	$157.82	5.534%	$166.5538	$166.55	$166.55	$166.60
7 purchase totals =	$750.88		$809.4037	$809.40	$809.40	$809.50