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	$98.60	5.331%	$103.8564	$103.86	$103.85	$103.90
Purchase #2	$137.31	4.575%	$143.5919	$143.59	$143.60	$143.60
Purchase #3	$60.82	4.737%	$63.701	$63.70	$63.70	$63.70
Purchase #4	$69.89	4.559%	$73.0763	$73.08	$73.10	$73.10
Purchase #5	$116.74	12.624%	$131.4773	$131.48	$131.50	$131.50
Purchase #6	$225.42	9.240%	$246.2488	$246.25	$246.25	$246.20
Purchase #7	$243.26	8.351%	$263.5746	$263.57	$263.55	$263.60
7 purchase totals =	$952.04		$1,025.5263	$1,025.53	$1,025.55	$1,025.60