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	$133.71	5.687%	$141.3141	$141.31	$141.30	$141.30
Purchase #2	$98.29	13.135%	$111.2004	$111.20	$111.20	$111.20
Purchase #3	$81.25	3.201%	$83.8508	$83.85	$83.85	$83.90
Purchase #4	$244.59	4.470%	$255.5232	$255.52	$255.50	$255.50
Purchase #5	$50.92	7.870%	$54.9274	$54.93	$54.95	$54.90
Purchase #6	$185.67	3.327%	$191.8472	$191.85	$191.85	$191.80
Purchase #7	$200.81	6.764%	$214.3928	$214.39	$214.40	$214.40
7 purchase totals =	$995.24		$1,053.0559	$1,053.05	$1,053.05	$1,053.00