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	$162.89	4.301%	$169.8959	$169.90	$169.90	$169.90
Purchase #2	$160.61	7.360%	$172.4309	$172.43	$172.45	$172.40
Purchase #3	$124.31	6.793%	$132.7544	$132.75	$132.75	$132.80
Purchase #4	$92.65	7.577%	$99.6701	$99.67	$99.65	$99.70
Purchase #5	$176.70	11.503%	$197.0258	$197.03	$197.05	$197.00
Purchase #6	$91.37	5.631%	$96.515	$96.52	$96.50	$96.50
Purchase #7	$234.52	8.821%	$255.207	$255.21	$255.20	$255.20
7 purchase totals =	$1,043.05		$1,123.4991	$1,123.51	$1,123.50	$1,123.50