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	$66.66	7.635%	$71.7495	$71.75	$71.75	$71.70
Purchase #2	$80.58	8.132%	$87.1328	$87.13	$87.15	$87.10
Purchase #3	$34.57	9.376%	$37.8113	$37.81	$37.80	$37.80
Purchase #4	$39.77	7.748%	$42.8514	$42.85	$42.85	$42.90
Purchase #5	$221.89	7.593%	$238.7381	$238.74	$238.75	$238.70
Purchase #6	$228.60	5.534%	$241.2507	$241.25	$241.25	$241.30
Purchase #7	$38.41	7.149%	$41.1559	$41.16	$41.15	$41.20
7 purchase totals =	$710.48		$760.6897	$760.69	$760.70	$760.70