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	$219.77	3.537%	$227.5433	$227.54	$227.55	$227.50
Purchase #2	$61.96	12.534%	$69.7261	$69.73	$69.75	$69.70
Purchase #3	$205.32	3.545%	$212.5986	$212.60	$212.60	$212.60
Purchase #4	$97.89	9.165%	$106.8616	$106.86	$106.85	$106.90
Purchase #5	$19.43	12.807%	$21.9184	$21.92	$21.90	$21.90
Purchase #6	$105.82	5.317%	$111.4464	$111.45	$111.45	$111.40
Purchase #7	$236.66	12.474%	$266.181	$266.18	$266.20	$266.20
7 purchase totals =	$946.85		$1,016.2754	$1,016.28	$1,016.30	$1,016.20