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	$163.31	6.504%	$173.9317	$173.93	$173.95	$173.90
Purchase #2	$190.81	5.227%	$200.7836	$200.78	$200.80	$200.80
Purchase #3	$132.74	7.307%	$142.4393	$142.44	$142.45	$142.40
Purchase #4	$95.29	5.858%	$100.8721	$100.87	$100.85	$100.90
Purchase #5	$31.81	10.557%	$35.1682	$35.17	$35.15	$35.20
Purchase #6	$205.57	12.379%	$231.0175	$231.02	$231.00	$231.00
Purchase #7	$128.27	10.349%	$141.5447	$141.54	$141.55	$141.50
7 purchase totals =	$947.80		$1,025.7571	$1,025.75	$1,025.75	$1,025.70