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	$168.54	7.542%	$181.2513	$181.25	$181.25	$181.30
Purchase #2	$59.64	11.431%	$66.4574	$66.46	$66.45	$66.50
Purchase #3	$235.93	6.553%	$251.3905	$251.39	$251.40	$251.40
Purchase #4	$159.82	3.645%	$165.6454	$165.65	$165.65	$165.60
Purchase #5	$57.59	13.865%	$65.5749	$65.57	$65.55	$65.60
Purchase #6	$199.35	7.195%	$213.6932	$213.69	$213.70	$213.70
Purchase #7	$120.29	3.572%	$124.5868	$124.59	$124.60	$124.60
7 purchase totals =	$1,001.16		$1,068.5995	$1,068.60	$1,068.60	$1,068.70