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	$156.47	11.625%	$174.6596	$174.66	$174.65	$174.70
Purchase #2	$86.48	3.553%	$89.5526	$89.55	$89.55	$89.60
Purchase #3	$156.33	11.326%	$174.0359	$174.04	$174.05	$174.00
Purchase #4	$145.88	8.704%	$158.5774	$158.58	$158.60	$158.60
Purchase #5	$169.85	8.290%	$183.9306	$183.93	$183.95	$183.90
Purchase #6	$205.96	11.320%	$229.2747	$229.27	$229.25	$229.30
Purchase #7	$129.89	10.646%	$143.7181	$143.72	$143.70	$143.70
7 purchase totals =	$1,050.86		$1,153.7489	$1,153.75	$1,153.75	$1,153.80