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	$176.64	5.160%	$185.7546	$185.75	$185.75	$185.80
Purchase #2	$75.39	4.185%	$78.5451	$78.55	$78.55	$78.50
Purchase #3	$181.91	5.300%	$191.5512	$191.55	$191.55	$191.60
Purchase #4	$217.38	10.677%	$240.5897	$240.59	$240.60	$240.60
Purchase #5	$188.76	12.667%	$212.6702	$212.67	$212.65	$212.70
Purchase #6	$244.95	4.181%	$255.1914	$255.19	$255.20	$255.20
Purchase #7	$41.68	4.458%	$43.5381	$43.54	$43.55	$43.50
7 purchase totals =	$1,126.71		$1,207.8403	$1,207.84	$1,207.85	$1,207.90