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	$44.94	4.353%	$46.8962	$46.90	$46.90	$46.90
Purchase #2	$171.54	4.282%	$178.8853	$178.89	$178.90	$178.90
Purchase #3	$185.42	3.357%	$191.6445	$191.64	$191.65	$191.60
Purchase #4	$245.60	3.437%	$254.0413	$254.04	$254.05	$254.00
Purchase #5	$217.44	3.225%	$224.4524	$224.45	$224.45	$224.50
Purchase #6	$21.89	4.204%	$22.8103	$22.81	$22.80	$22.80
Purchase #7	$86.89	6.461%	$92.504	$92.50	$92.50	$92.50
7 purchase totals =	$973.72		$1,011.2340	$1,011.23	$1,011.25	$1,011.20