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	$229.35	7.106%	$245.6476	$245.65	$245.65	$245.60
Purchase #2	$154.96	11.452%	$172.706	$172.71	$172.70	$172.70
Purchase #3	$146.94	5.294%	$154.719	$154.72	$154.70	$154.70
Purchase #4	$52.96	6.794%	$56.5581	$56.56	$56.55	$56.60
Purchase #5	$74.75	4.411%	$78.0472	$78.05	$78.05	$78.00
Purchase #6	$69.39	3.837%	$72.0525	$72.05	$72.05	$72.10
Purchase #7	$218.56	9.639%	$239.627	$239.63	$239.65	$239.60
7 purchase totals =	$946.91		$1,019.3574	$1,019.37	$1,019.35	$1,019.30