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	$147.63	9.136%	$161.1175	$161.12	$161.10	$161.10
Purchase #2	$76.47	11.258%	$85.079	$85.08	$85.10	$85.10
Purchase #3	$82.66	9.594%	$90.5904	$90.59	$90.60	$90.60
Purchase #4	$85.32	6.851%	$91.1653	$91.17	$91.15	$91.20
Purchase #5	$88.97	10.292%	$98.1268	$98.13	$98.15	$98.10
Purchase #6	$198.35	12.661%	$223.4631	$223.46	$223.45	$223.50
Purchase #7	$190.49	3.256%	$196.6924	$196.69	$196.70	$196.70
7 purchase totals =	$869.89		$946.2345	$946.24	$946.25	$946.30