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	$188.83	8.857%	$205.5547	$205.55	$205.55	$205.60
Purchase #2	$135.84	5.652%	$143.5177	$143.52	$143.50	$143.50
Purchase #3	$74.58	5.264%	$78.5059	$78.51	$78.50	$78.50
Purchase #4	$189.68	5.111%	$199.3745	$199.37	$199.35	$199.40
Purchase #5	$62.94	3.118%	$64.9025	$64.90	$64.90	$64.90
Purchase #6	$232.71	8.189%	$251.7666	$251.77	$251.75	$251.80
Purchase #7	$76.70	6.773%	$81.8949	$81.89	$81.90	$81.90
7 purchase totals =	$961.28		$1,025.5168	$1,025.51	$1,025.45	$1,025.60