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	$153.43	5.459%	$161.8057	$161.81	$161.80	$161.80
Purchase #2	$151.74	4.712%	$158.89	$158.89	$158.90	$158.90
Purchase #3	$194.75	5.266%	$205.0055	$205.01	$205.00	$205.00
Purchase #4	$96.60	6.731%	$103.1021	$103.10	$103.10	$103.10
Purchase #5	$148.52	9.461%	$162.5715	$162.57	$162.55	$162.60
Purchase #6	$238.35	4.536%	$249.1616	$249.16	$249.15	$249.20
Purchase #7	$141.82	9.765%	$155.6687	$155.67	$155.65	$155.70
7 purchase totals =	$1,125.21		$1,196.2051	$1,196.21	$1,196.15	$1,196.30