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	$219.28	3.864%	$227.753	$227.75	$227.75	$227.80
Purchase #2	$126.90	13.765%	$144.3678	$144.37	$144.35	$144.40
Purchase #3	$69.70	7.818%	$75.1491	$75.15	$75.15	$75.10
Purchase #4	$28.28	10.508%	$31.2517	$31.25	$31.25	$31.30
Purchase #5	$99.92	11.236%	$111.147	$111.15	$111.15	$111.10
Purchase #6	$108.72	4.591%	$113.7113	$113.71	$113.70	$113.70
Purchase #7	$19.39	11.299%	$21.5809	$21.58	$21.60	$21.60
7 purchase totals =	$672.19		$724.9608	$724.96	$724.95	$725.00