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	$248.62	5.399%	$262.043	$262.04	$262.05	$262.00
Purchase #2	$247.46	6.447%	$263.4137	$263.41	$263.40	$263.40
Purchase #3	$28.96	12.593%	$32.6069	$32.61	$32.60	$32.60
Purchase #4	$132.25	7.859%	$142.6435	$142.64	$142.65	$142.60
Purchase #5	$234.76	11.342%	$261.3865	$261.39	$261.40	$261.40
Purchase #6	$40.67	7.834%	$43.8561	$43.86	$43.85	$43.90
Purchase #7	$9.80	4.452%	$10.2363	$10.24	$10.25	$10.20
7 purchase totals =	$942.52		$1,016.1860	$1,016.19	$1,016.20	$1,016.10