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	$163.29	10.481%	$180.4044	$180.40	$180.40	$180.40
Purchase #2	$244.33	7.409%	$262.4324	$262.43	$262.45	$262.40
Purchase #3	$155.57	5.713%	$164.4577	$164.46	$164.45	$164.50
Purchase #4	$96.89	6.541%	$103.2276	$103.23	$103.25	$103.20
Purchase #5	$143.35	13.279%	$162.3854	$162.39	$162.40	$162.40
Purchase #6	$111.46	10.204%	$122.8334	$122.83	$122.85	$122.80
Purchase #7	$196.44	11.373%	$218.7811	$218.78	$218.80	$218.80
7 purchase totals =	$1,111.33		$1,214.5220	$1,214.52	$1,214.60	$1,214.50