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	$153.48	5.360%	$161.7065	$161.71	$161.70	$161.70
Purchase #2	$119.42	7.600%	$128.4959	$128.50	$128.50	$128.50
Purchase #3	$141.38	6.482%	$150.5443	$150.54	$150.55	$150.50
Purchase #4	$148.88	3.161%	$153.5861	$153.59	$153.60	$153.60
Purchase #5	$246.29	3.560%	$255.0579	$255.06	$255.05	$255.10
Purchase #6	$199.79	12.758%	$225.2792	$225.28	$225.30	$225.30
Purchase #7	$200.73	11.539%	$223.8922	$223.89	$223.90	$223.90
7 purchase totals =	$1,209.97		$1,298.5621	$1,298.57	$1,298.60	$1,298.60