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	$40.45	8.601%	$43.9291	$43.93	$43.95	$43.90
Purchase #2	$92.81	4.231%	$96.7368	$96.74	$96.75	$96.70
Purchase #3	$50.42	7.606%	$54.2549	$54.25	$54.25	$54.30
Purchase #4	$234.86	9.209%	$256.4883	$256.49	$256.50	$256.50
Purchase #5	$206.61	10.217%	$227.7193	$227.72	$227.70	$227.70
Purchase #6	$241.96	10.247%	$266.7536	$266.75	$266.75	$266.80
Purchase #7	$250.76	5.304%	$264.0603	$264.06	$264.05	$264.10
7 purchase totals =	$1,117.87		$1,209.9423	$1,209.94	$1,209.95	$1,210.00