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	$194.63	9.228%	$212.5905	$212.59	$212.60	$212.60
Purchase #2	$215.78	9.754%	$236.8272	$236.83	$236.85	$236.80
Purchase #3	$179.68	3.395%	$185.7801	$185.78	$185.80	$185.80
Purchase #4	$176.31	7.790%	$190.0445	$190.04	$190.05	$190.00
Purchase #5	$236.50	13.758%	$269.0377	$269.04	$269.05	$269.00
Purchase #6	$141.88	7.488%	$152.504	$152.50	$152.50	$152.50
Purchase #7	$61.59	5.865%	$65.2023	$65.20	$65.20	$65.20
7 purchase totals =	$1,206.37		$1,311.9863	$1,311.98	$1,312.05	$1,311.90