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	$118.85	7.372%	$127.6116	$127.61	$127.60	$127.60
Purchase #2	$6.96	7.828%	$7.5048	$7.50	$7.50	$7.50
Purchase #3	$70.62	8.327%	$76.5005	$76.50	$76.50	$76.50
Purchase #4	$160.61	9.792%	$176.3369	$176.34	$176.35	$176.30
Purchase #5	$80.34	5.184%	$84.5048	$84.50	$84.50	$84.50
Purchase #6	$49.45	8.267%	$53.538	$53.54	$53.55	$53.50
Purchase #7	$243.65	8.149%	$263.505	$263.51	$263.50	$263.50
7 purchase totals =	$730.48		$789.5016	$789.50	$789.50	$789.40