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	$131.50	7.565%	$141.448	$141.45	$141.45	$141.40
Purchase #2	$110.32	12.384%	$123.982	$123.98	$124.00	$124.00
Purchase #3	$34.61	8.350%	$37.4999	$37.50	$37.50	$37.50
Purchase #4	$106.90	11.531%	$119.2266	$119.23	$119.25	$119.20
Purchase #5	$246.49	10.664%	$272.7757	$272.78	$272.80	$272.80
Purchase #6	$131.43	5.680%	$138.8952	$138.90	$138.90	$138.90
Purchase #7	$203.61	7.616%	$219.1169	$219.12	$219.10	$219.10
7 purchase totals =	$964.86		$1,052.9443	$1,052.96	$1,053.00	$1,052.90