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	$54.69	13.429%	$62.0343	$62.03	$62.05	$62.00
Purchase #2	$68.65	4.718%	$71.8889	$71.89	$71.90	$71.90
Purchase #3	$30.86	5.767%	$32.6397	$32.64	$32.65	$32.60
Purchase #4	$205.67	10.666%	$227.6068	$227.61	$227.60	$227.60
Purchase #5	$59.69	9.371%	$65.2835	$65.28	$65.30	$65.30
Purchase #6	$125.80	4.587%	$131.5704	$131.57	$131.55	$131.60
Purchase #7	$214.33	5.597%	$226.3261	$226.33	$226.35	$226.30
7 purchase totals =	$759.69		$817.3497	$817.35	$817.40	$817.30