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	$193.61	9.561%	$212.1211	$212.12	$212.10	$212.10
Purchase #2	$10.96	4.232%	$11.4238	$11.42	$11.40	$11.40
Purchase #3	$62.63	3.109%	$64.5772	$64.58	$64.60	$64.60
Purchase #4	$8.78	5.105%	$9.2282	$9.23	$9.25	$9.20
Purchase #5	$159.86	3.520%	$165.4871	$165.49	$165.50	$165.50
Purchase #6	$43.35	7.308%	$46.518	$46.52	$46.50	$46.50
Purchase #7	$53.64	7.241%	$57.5241	$57.52	$57.50	$57.50
7 purchase totals =	$532.83		$566.8795	$566.88	$566.85	$566.80