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	$233.69	4.771%	$244.8393	$244.84	$244.85	$244.80
Purchase #2	$103.65	5.311%	$109.1549	$109.15	$109.15	$109.20
Purchase #3	$11.47	9.795%	$12.5935	$12.59	$12.60	$12.60
Purchase #4	$212.40	5.266%	$223.585	$223.59	$223.60	$223.60
Purchase #5	$150.52	13.140%	$170.2983	$170.30	$170.30	$170.30
Purchase #6	$110.39	6.766%	$117.859	$117.86	$117.85	$117.90
Purchase #7	$168.66	13.211%	$190.9417	$190.94	$190.95	$190.90
7 purchase totals =	$990.78		$1,069.2717	$1,069.27	$1,069.30	$1,069.30