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	$181.92	7.779%	$196.0716	$196.07	$196.05	$196.10
Purchase #2	$86.78	4.201%	$90.4256	$90.43	$90.45	$90.40
Purchase #3	$127.32	6.434%	$135.5118	$135.51	$135.50	$135.50
Purchase #4	$205.78	3.473%	$212.9267	$212.93	$212.95	$212.90
Purchase #5	$48.49	3.636%	$50.2531	$50.25	$50.25	$50.30
Purchase #6	$231.77	10.129%	$255.246	$255.25	$255.25	$255.20
Purchase #7	$119.54	7.428%	$128.4194	$128.42	$128.40	$128.40
7 purchase totals =	$1,001.60		$1,068.8542	$1,068.86	$1,068.85	$1,068.80