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	$178.76	4.792%	$187.3262	$187.33	$187.35	$187.30
Purchase #2	$214.35	8.473%	$232.5119	$232.51	$232.50	$232.50
Purchase #3	$112.37	13.752%	$127.8231	$127.82	$127.80	$127.80
Purchase #4	$181.31	13.385%	$205.5783	$205.58	$205.60	$205.60
Purchase #5	$161.85	10.852%	$179.414	$179.41	$179.40	$179.40
Purchase #6	$43.71	5.571%	$46.1451	$46.15	$46.15	$46.10
Purchase #7	$180.86	4.501%	$189.0005	$189.00	$189.00	$189.00
7 purchase totals =	$1,073.21		$1,167.7991	$1,167.80	$1,167.80	$1,167.70