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	$230.64	9.502%	$252.5554	$252.56	$252.55	$252.60
Purchase #2	$103.78	7.351%	$111.4089	$111.41	$111.40	$111.40
Purchase #3	$39.34	7.434%	$42.2645	$42.26	$42.25	$42.30
Purchase #4	$203.64	10.480%	$224.9815	$224.98	$225.00	$225.00
Purchase #5	$234.73	11.435%	$261.5714	$261.57	$261.55	$261.60
Purchase #6	$85.86	5.425%	$90.5179	$90.52	$90.50	$90.50
Purchase #7	$206.46	13.338%	$233.9976	$234.00	$234.00	$234.00
7 purchase totals =	$1,104.45		$1,217.2972	$1,217.30	$1,217.25	$1,217.40