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	$148.49	13.386%	$168.3669	$168.37	$168.35	$168.40
Purchase #2	$63.71	13.103%	$72.0579	$72.06	$72.05	$72.10
Purchase #3	$54.46	9.382%	$59.5694	$59.57	$59.55	$59.60
Purchase #4	$69.97	5.260%	$73.6504	$73.65	$73.65	$73.70
Purchase #5	$221.55	7.844%	$238.9284	$238.93	$238.95	$238.90
Purchase #6	$243.64	7.550%	$262.0348	$262.03	$262.05	$262.00
Purchase #7	$227.37	6.328%	$241.758	$241.76	$241.75	$241.80
7 purchase totals =	$1,029.19		$1,116.3658	$1,116.37	$1,116.35	$1,116.50