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	$209.79	8.360%	$227.3284	$227.33	$227.35	$227.30
Purchase #2	$212.73	4.646%	$222.6134	$222.61	$222.60	$222.60
Purchase #3	$107.72	4.336%	$112.3907	$112.39	$112.40	$112.40
Purchase #4	$99.46	4.408%	$103.8442	$103.84	$103.85	$103.80
Purchase #5	$206.36	8.536%	$223.9749	$223.97	$223.95	$224.00
Purchase #6	$102.67	9.871%	$112.8046	$112.80	$112.80	$112.80
Purchase #7	$138.70	4.177%	$144.4935	$144.49	$144.50	$144.50
7 purchase totals =	$1,077.43		$1,147.4497	$1,147.43	$1,147.45	$1,147.40