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	$96.51	13.616%	$109.6508	$109.65	$109.65	$109.70
Purchase #2	$97.77	13.559%	$111.0266	$111.03	$111.05	$111.00
Purchase #3	$156.66	8.823%	$170.4821	$170.48	$170.50	$170.50
Purchase #4	$119.39	5.194%	$125.5911	$125.59	$125.60	$125.60
Purchase #5	$207.86	12.824%	$234.516	$234.52	$234.50	$234.50
Purchase #6	$205.38	7.552%	$220.8903	$220.89	$220.90	$220.90
Purchase #7	$51.46	10.467%	$56.8463	$56.85	$56.85	$56.80
7 purchase totals =	$935.03		$1,029.0032	$1,029.01	$1,029.05	$1,029.00