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	$228.50	5.759%	$241.6593	$241.66	$241.65	$241.70
Purchase #2	$204.28	4.819%	$214.1243	$214.12	$214.10	$214.10
Purchase #3	$226.42	6.197%	$240.4512	$240.45	$240.45	$240.50
Purchase #4	$28.25	3.443%	$29.2226	$29.22	$29.20	$29.20
Purchase #5	$48.25	12.618%	$54.3382	$54.34	$54.35	$54.30
Purchase #6	$48.40	5.206%	$50.9197	$50.92	$50.90	$50.90
Purchase #7	$103.53	7.346%	$111.1353	$111.14	$111.15	$111.10
7 purchase totals =	$887.63		$941.8506	$941.85	$941.80	$941.80