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	$106.54	9.663%	$116.835	$116.84	$116.85	$116.80
Purchase #2	$55.73	5.450%	$58.7673	$58.77	$58.75	$58.80
Purchase #3	$188.60	13.791%	$214.6098	$214.61	$214.60	$214.60
Purchase #4	$108.43	8.406%	$117.5446	$117.54	$117.55	$117.50
Purchase #5	$58.33	12.373%	$65.5472	$65.55	$65.55	$65.50
Purchase #6	$206.32	12.378%	$231.8583	$231.86	$231.85	$231.90
Purchase #7	$205.95	3.844%	$213.8667	$213.87	$213.85	$213.90
7 purchase totals =	$929.90		$1,019.0289	$1,019.04	$1,019.00	$1,019.00