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	$185.50	5.551%	$195.7971	$195.80	$195.80	$195.80
Purchase #2	$161.76	12.758%	$182.3973	$182.40	$182.40	$182.40
Purchase #3	$178.85	13.829%	$203.5832	$203.58	$203.60	$203.60
Purchase #4	$71.84	9.358%	$78.5628	$78.56	$78.55	$78.60
Purchase #5	$131.92	11.321%	$146.8547	$146.85	$146.85	$146.90
Purchase #6	$116.58	13.414%	$132.218	$132.22	$132.20	$132.20
Purchase #7	$161.27	3.791%	$167.3837	$167.38	$167.40	$167.40
7 purchase totals =	$1,007.72		$1,106.7968	$1,106.79	$1,106.80	$1,106.90