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	$102.54	3.268%	$105.891	$105.89	$105.90	$105.90
Purchase #2	$119.34	5.178%	$125.5194	$125.52	$125.50	$125.50
Purchase #3	$237.98	13.217%	$269.4338	$269.43	$269.45	$269.40
Purchase #4	$118.57	3.846%	$123.1302	$123.13	$123.15	$123.10
Purchase #5	$145.54	13.206%	$164.76	$164.76	$164.75	$164.80
Purchase #6	$138.68	13.218%	$157.0107	$157.01	$157.00	$157.00
Purchase #7	$70.59	5.554%	$74.5106	$74.51	$74.50	$74.50
7 purchase totals =	$933.24		$1,020.2557	$1,020.25	$1,020.25	$1,020.20