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	$152.51	3.233%	$157.4406	$157.44	$157.45	$157.40
Purchase #2	$168.37	13.660%	$191.3693	$191.37	$191.35	$191.40
Purchase #3	$214.54	8.835%	$233.4946	$233.49	$233.50	$233.50
Purchase #4	$191.28	6.653%	$204.0059	$204.01	$204.00	$204.00
Purchase #5	$94.30	4.581%	$98.6199	$98.62	$98.60	$98.60
Purchase #6	$36.29	11.586%	$40.4946	$40.49	$40.50	$40.50
Purchase #7	$90.57	10.241%	$99.8453	$99.85	$99.85	$99.80
7 purchase totals =	$947.86		$1,025.2702	$1,025.27	$1,025.25	$1,025.20