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	$184.72	6.496%	$196.7194	$196.72	$196.70	$196.70
Purchase #2	$240.37	10.689%	$266.0631	$266.06	$266.05	$266.10
Purchase #3	$240.39	7.583%	$258.6188	$258.62	$258.60	$258.60
Purchase #4	$97.89	6.260%	$104.0179	$104.02	$104.00	$104.00
Purchase #5	$232.68	10.283%	$256.6065	$256.61	$256.60	$256.60
Purchase #6	$102.37	4.125%	$106.5928	$106.59	$106.60	$106.60
Purchase #7	$228.78	5.112%	$240.4752	$240.48	$240.50	$240.50
7 purchase totals =	$1,327.20		$1,429.0937	$1,429.10	$1,429.05	$1,429.10