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	$200.38	5.753%	$211.9079	$211.91	$211.90	$211.90
Purchase #2	$39.35	5.366%	$41.4615	$41.46	$41.45	$41.50
Purchase #3	$209.29	3.236%	$216.0626	$216.06	$216.05	$216.10
Purchase #4	$95.64	13.545%	$108.5944	$108.59	$108.60	$108.60
Purchase #5	$13.33	4.204%	$13.8904	$13.89	$13.90	$13.90
Purchase #6	$87.71	12.805%	$98.9413	$98.94	$98.95	$98.90
Purchase #7	$200.45	6.483%	$213.4452	$213.45	$213.45	$213.40
7 purchase totals =	$846.15		$904.3033	$904.30	$904.30	$904.30