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	$40.96	13.251%	$46.3876	$46.39	$46.40	$46.40
Purchase #2	$240.64	6.714%	$256.7966	$256.80	$256.80	$256.80
Purchase #3	$178.65	11.546%	$199.2769	$199.28	$199.30	$199.30
Purchase #4	$187.67	12.408%	$210.9561	$210.96	$210.95	$211.00
Purchase #5	$107.77	4.344%	$112.4515	$112.45	$112.45	$112.50
Purchase #6	$103.37	6.169%	$109.7469	$109.75	$109.75	$109.70
Purchase #7	$208.75	9.469%	$228.5165	$228.52	$228.50	$228.50
7 purchase totals =	$1,067.81		$1,164.1321	$1,164.15	$1,164.15	$1,164.20