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	$218.70	10.385%	$241.412	$241.41	$241.40	$241.40
Purchase #2	$176.97	9.562%	$193.8919	$193.89	$193.90	$193.90
Purchase #3	$75.36	13.615%	$85.6203	$85.62	$85.60	$85.60
Purchase #4	$105.61	5.671%	$111.5991	$111.60	$111.60	$111.60
Purchase #5	$194.48	9.187%	$212.3469	$212.35	$212.35	$212.30
Purchase #6	$56.89	9.863%	$62.5011	$62.50	$62.50	$62.50
Purchase #7	$176.38	7.473%	$189.5609	$189.56	$189.55	$189.60
7 purchase totals =	$1,004.39		$1,096.9322	$1,096.93	$1,096.90	$1,096.90