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	$227.62	7.175%	$243.9517	$243.95	$243.95	$244.00
Purchase #2	$181.64	3.395%	$187.8067	$187.81	$187.80	$187.80
Purchase #3	$134.64	5.248%	$141.7059	$141.71	$141.70	$141.70
Purchase #4	$109.37	6.178%	$116.1269	$116.13	$116.15	$116.10
Purchase #5	$42.79	10.222%	$47.164	$47.16	$47.15	$47.20
Purchase #6	$200.91	11.534%	$224.083	$224.08	$224.10	$224.10
Purchase #7	$139.64	7.759%	$150.4747	$150.47	$150.45	$150.50
7 purchase totals =	$1,036.61		$1,111.3129	$1,111.31	$1,111.30	$1,111.40