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	$86.64	9.573%	$94.934	$94.93	$94.95	$94.90
Purchase #2	$52.39	6.792%	$55.9483	$55.95	$55.95	$55.90
Purchase #3	$125.71	4.127%	$130.8981	$130.90	$130.90	$130.90
Purchase #4	$192.94	4.104%	$200.8583	$200.86	$200.85	$200.90
Purchase #5	$242.59	9.852%	$266.49	$266.49	$266.50	$266.50
Purchase #6	$191.31	3.833%	$198.6429	$198.64	$198.65	$198.60
Purchase #7	$128.60	7.578%	$138.3453	$138.35	$138.35	$138.30
7 purchase totals =	$1,020.18		$1,086.1169	$1,086.12	$1,086.15	$1,086.00