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	$206.32	8.830%	$224.5381	$224.54	$224.55	$224.50
Purchase #2	$206.89	9.869%	$227.308	$227.31	$227.30	$227.30
Purchase #3	$108.71	5.680%	$114.8847	$114.88	$114.90	$114.90
Purchase #4	$196.62	7.571%	$211.5061	$211.51	$211.50	$211.50
Purchase #5	$72.76	5.782%	$76.967	$76.97	$76.95	$77.00
Purchase #6	$99.75	4.449%	$104.1879	$104.19	$104.20	$104.20
Purchase #7	$131.60	4.210%	$137.1404	$137.14	$137.15	$137.10
7 purchase totals =	$1,022.65		$1,096.5322	$1,096.54	$1,096.55	$1,096.50