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	$89.67	13.564%	$101.8328	$101.83	$101.85	$101.80
Purchase #2	$139.86	4.212%	$145.7509	$145.75	$145.75	$145.80
Purchase #3	$184.96	8.478%	$200.6409	$200.64	$200.65	$200.60
Purchase #4	$185.42	7.742%	$199.7752	$199.78	$199.80	$199.80
Purchase #5	$41.35	4.137%	$43.0606	$43.06	$43.05	$43.10
Purchase #6	$164.69	13.269%	$186.5427	$186.54	$186.55	$186.50
Purchase #7	$174.84	13.304%	$198.1007	$198.10	$198.10	$198.10
7 purchase totals =	$980.79		$1,075.7038	$1,075.70	$1,075.75	$1,075.70