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	$216.81	5.831%	$229.4522	$229.45	$229.45	$229.50
Purchase #2	$99.91	13.440%	$113.3379	$113.34	$113.35	$113.30
Purchase #3	$197.38	12.670%	$222.388	$222.39	$222.40	$222.40
Purchase #4	$196.85	4.446%	$205.602	$205.60	$205.60	$205.60
Purchase #5	$29.31	4.729%	$30.6961	$30.70	$30.70	$30.70
Purchase #6	$121.32	3.779%	$125.9047	$125.90	$125.90	$125.90
Purchase #7	$41.57	8.598%	$45.1442	$45.14	$45.15	$45.10
7 purchase totals =	$903.15		$972.5251	$972.52	$972.55	$972.50