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	$94.50	12.493%	$106.3059	$106.31	$106.30	$106.30
Purchase #2	$62.43	9.427%	$68.3153	$68.32	$68.30	$68.30
Purchase #3	$43.78	10.690%	$48.4601	$48.46	$48.45	$48.50
Purchase #4	$131.27	4.466%	$137.1325	$137.13	$137.15	$137.10
Purchase #5	$125.85	4.498%	$131.5107	$131.51	$131.50	$131.50
Purchase #6	$233.82	12.284%	$262.5424	$262.54	$262.55	$262.50
Purchase #7	$244.64	6.338%	$260.1453	$260.15	$260.15	$260.10
7 purchase totals =	$936.29		$1,014.4122	$1,014.42	$1,014.40	$1,014.30