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	$212.34	10.819%	$235.3131	$235.31	$235.30	$235.30
Purchase #2	$210.58	12.317%	$236.5171	$236.52	$236.50	$236.50
Purchase #3	$32.51	3.381%	$33.6092	$33.61	$33.60	$33.60
Purchase #4	$154.51	11.677%	$172.5521	$172.55	$172.55	$172.60
Purchase #5	$30.81	6.654%	$32.8601	$32.86	$32.85	$32.90
Purchase #6	$171.42	12.704%	$193.1972	$193.20	$193.20	$193.20
Purchase #7	$171.43	11.439%	$191.0399	$191.04	$191.05	$191.00
7 purchase totals =	$983.60		$1,095.0887	$1,095.09	$1,095.05	$1,095.10