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	$190.35	8.209%	$205.9758	$205.98	$206.00	$206.00
Purchase #2	$175.71	5.557%	$185.4742	$185.47	$185.45	$185.50
Purchase #3	$168.38	10.250%	$185.639	$185.64	$185.65	$185.60
Purchase #4	$40.60	10.560%	$44.8874	$44.89	$44.90	$44.90
Purchase #5	$20.85	4.607%	$21.8106	$21.81	$21.80	$21.80
Purchase #6	$209.48	5.488%	$220.9763	$220.98	$221.00	$221.00
Purchase #7	$142.75	3.277%	$147.4279	$147.43	$147.45	$147.40
7 purchase totals =	$948.12		$1,012.1912	$1,012.20	$1,012.25	$1,012.20