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	$169.25	13.408%	$191.943	$191.94	$191.95	$191.90
Purchase #2	$62.29	3.808%	$64.662	$64.66	$64.65	$64.70
Purchase #3	$37.74	13.555%	$42.8557	$42.86	$42.85	$42.90
Purchase #4	$130.88	9.459%	$143.2599	$143.26	$143.25	$143.30
Purchase #5	$222.89	5.776%	$235.7641	$235.76	$235.75	$235.80
Purchase #6	$84.99	6.425%	$90.4506	$90.45	$90.45	$90.50
Purchase #7	$108.98	12.728%	$122.851	$122.85	$122.85	$122.90
7 purchase totals =	$817.02		$891.7863	$891.78	$891.75	$892.00