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	$72.62	4.564%	$75.9344	$75.93	$75.95	$75.90
Purchase #2	$96.46	4.359%	$100.6647	$100.66	$100.65	$100.70
Purchase #3	$139.32	9.646%	$152.7588	$152.76	$152.75	$152.80
Purchase #4	$149.96	7.321%	$160.9386	$160.94	$160.95	$160.90
Purchase #5	$183.39	12.107%	$205.593	$205.59	$205.60	$205.60
Purchase #6	$80.85	11.149%	$89.864	$89.86	$89.85	$89.90
Purchase #7	$132.90	7.418%	$142.7585	$142.76	$142.75	$142.80
7 purchase totals =	$855.50		$928.5120	$928.50	$928.50	$928.60