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	$228.94	4.185%	$238.5211	$238.52	$238.50	$238.50
Purchase #2	$6.62	10.807%	$7.3354	$7.34	$7.35	$7.30
Purchase #3	$113.41	4.461%	$118.4692	$118.47	$118.45	$118.50
Purchase #4	$77.87	5.445%	$82.11	$82.11	$82.10	$82.10
Purchase #5	$111.64	4.131%	$116.2518	$116.25	$116.25	$116.30
Purchase #6	$177.88	11.861%	$198.9783	$198.98	$199.00	$199.00
Purchase #7	$249.77	8.395%	$270.7382	$270.74	$270.75	$270.70
7 purchase totals =	$966.13		$1,032.4040	$1,032.41	$1,032.40	$1,032.40