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	$214.81	10.810%	$238.031	$238.03	$238.05	$238.00
Purchase #2	$122.85	7.116%	$131.592	$131.59	$131.60	$131.60
Purchase #3	$90.63	5.790%	$95.8775	$95.88	$95.90	$95.90
Purchase #4	$213.74	13.501%	$242.597	$242.60	$242.60	$242.60
Purchase #5	$33.66	11.256%	$37.4488	$37.45	$37.45	$37.40
Purchase #6	$81.53	11.829%	$91.1742	$91.17	$91.15	$91.20
Purchase #7	$193.89	4.334%	$202.2932	$202.29	$202.30	$202.30
7 purchase totals =	$951.11		$1,039.0137	$1,039.01	$1,039.05	$1,039.00