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	$182.94	7.240%	$196.1849	$196.18	$196.20	$196.20
Purchase #2	$69.64	7.109%	$74.5907	$74.59	$74.60	$74.60
Purchase #3	$198.29	5.373%	$208.9441	$208.94	$208.95	$208.90
Purchase #4	$123.41	7.122%	$132.1993	$132.20	$132.20	$132.20
Purchase #5	$204.73	7.206%	$219.4828	$219.48	$219.50	$219.50
Purchase #6	$108.47	13.867%	$123.5115	$123.51	$123.50	$123.50
Purchase #7	$212.95	6.826%	$227.486	$227.49	$227.50	$227.50
7 purchase totals =	$1,100.43		$1,182.3993	$1,182.39	$1,182.45	$1,182.40