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	$212.59	4.736%	$222.6583	$222.66	$222.65	$222.70
Purchase #2	$182.32	11.544%	$203.367	$203.37	$203.35	$203.40
Purchase #3	$46.49	10.735%	$51.4807	$51.48	$51.50	$51.50
Purchase #4	$172.59	11.741%	$192.8538	$192.85	$192.85	$192.90
Purchase #5	$200.99	11.403%	$223.9089	$223.91	$223.90	$223.90
Purchase #6	$55.67	6.668%	$59.3821	$59.38	$59.40	$59.40
Purchase #7	$126.35	12.744%	$142.452	$142.45	$142.45	$142.50
7 purchase totals =	$997.00		$1,096.1028	$1,096.10	$1,096.10	$1,096.30