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	$12.74	9.676%	$13.9727	$13.97	$13.95	$14.00
Purchase #2	$65.33	9.119%	$71.2874	$71.29	$71.30	$71.30
Purchase #3	$102.34	4.811%	$107.2636	$107.26	$107.25	$107.30
Purchase #4	$115.71	6.363%	$123.0726	$123.07	$123.05	$123.10
Purchase #5	$142.41	5.664%	$150.4761	$150.48	$150.50	$150.50
Purchase #6	$174.85	12.536%	$196.7692	$196.77	$196.75	$196.80
Purchase #7	$52.29	12.191%	$58.6647	$58.66	$58.65	$58.70
7 purchase totals =	$665.67		$721.5063	$721.50	$721.45	$721.70