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	$151.61	13.479%	$172.0455	$172.05	$172.05	$172.00
Purchase #2	$31.50	3.854%	$32.714	$32.71	$32.70	$32.70
Purchase #3	$250.54	7.729%	$269.9042	$269.90	$269.90	$269.90
Purchase #4	$155.51	10.346%	$171.5991	$171.60	$171.60	$171.60
Purchase #5	$214.48	5.808%	$226.937	$226.94	$226.95	$226.90
Purchase #6	$203.42	11.849%	$227.5232	$227.52	$227.50	$227.50
Purchase #7	$239.72	10.356%	$264.5454	$264.55	$264.55	$264.50
7 purchase totals =	$1,246.78		$1,365.2684	$1,365.27	$1,365.25	$1,365.10