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	$106.53	3.331%	$110.0785	$110.08	$110.10	$110.10
Purchase #2	$11.48	12.246%	$12.8858	$12.89	$12.90	$12.90
Purchase #3	$72.60	8.268%	$78.6026	$78.60	$78.60	$78.60
Purchase #4	$42.69	10.606%	$47.2177	$47.22	$47.20	$47.20
Purchase #5	$128.52	3.290%	$132.7483	$132.75	$132.75	$132.70
Purchase #6	$46.35	11.353%	$51.6121	$51.61	$51.60	$51.60
Purchase #7	$215.87	12.764%	$243.4236	$243.42	$243.40	$243.40
7 purchase totals =	$624.04		$676.5686	$676.57	$676.55	$676.50