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	$112.57	9.773%	$123.5715	$123.57	$123.55	$123.60
Purchase #2	$70.68	3.136%	$72.8965	$72.90	$72.90	$72.90
Purchase #3	$242.43	3.553%	$251.0435	$251.04	$251.05	$251.00
Purchase #4	$183.63	13.327%	$208.1024	$208.10	$208.10	$208.10
Purchase #5	$147.26	13.485%	$167.118	$167.12	$167.10	$167.10
Purchase #6	$192.88	13.263%	$218.4617	$218.46	$218.45	$218.50
Purchase #7	$15.91	11.715%	$17.7739	$17.77	$17.75	$17.80
7 purchase totals =	$965.36		$1,058.9675	$1,058.96	$1,058.90	$1,059.00