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	$69.39	13.757%	$78.936	$78.94	$78.95	$78.90
Purchase #2	$79.37	13.851%	$90.3635	$90.36	$90.35	$90.40
Purchase #3	$120.41	10.166%	$132.6509	$132.65	$132.65	$132.70
Purchase #4	$175.78	12.497%	$197.7472	$197.75	$197.75	$197.70
Purchase #5	$212.90	5.729%	$225.097	$225.10	$225.10	$225.10
Purchase #6	$163.90	4.113%	$170.6412	$170.64	$170.65	$170.60
Purchase #7	$167.70	13.757%	$190.7705	$190.77	$190.75	$190.80
7 purchase totals =	$989.45		$1,086.2063	$1,086.21	$1,086.20	$1,086.20