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	$235.86	7.476%	$253.4929	$253.49	$253.50	$253.50
Purchase #2	$48.84	13.636%	$55.4998	$55.50	$55.50	$55.50
Purchase #3	$114.73	7.689%	$123.5516	$123.55	$123.55	$123.60
Purchase #4	$158.80	11.529%	$177.1081	$177.11	$177.10	$177.10
Purchase #5	$84.28	6.446%	$89.7127	$89.71	$89.70	$89.70
Purchase #6	$236.75	4.156%	$246.5893	$246.59	$246.60	$246.60
Purchase #7	$80.88	12.638%	$91.1016	$91.10	$91.10	$91.10
7 purchase totals =	$960.14		$1,037.0560	$1,037.05	$1,037.05	$1,037.10