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	$180.25	4.140%	$187.7124	$187.71	$187.70	$187.70
Purchase #2	$89.33	13.434%	$101.3306	$101.33	$101.35	$101.30
Purchase #3	$105.67	8.701%	$114.8643	$114.86	$114.85	$114.90
Purchase #4	$166.51	3.672%	$172.6242	$172.62	$172.60	$172.60
Purchase #5	$52.87	4.512%	$55.2555	$55.26	$55.25	$55.30
Purchase #6	$163.41	4.683%	$171.0625	$171.06	$171.05	$171.10
Purchase #7	$225.94	8.723%	$245.6487	$245.65	$245.65	$245.60
7 purchase totals =	$983.98		$1,048.4982	$1,048.49	$1,048.45	$1,048.50