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	$41.27	7.761%	$44.473	$44.47	$44.45	$44.50
Purchase #2	$135.54	4.156%	$141.173	$141.17	$141.15	$141.20
Purchase #3	$184.89	13.119%	$209.1457	$209.15	$209.15	$209.10
Purchase #4	$95.83	3.248%	$98.9426	$98.94	$98.95	$98.90
Purchase #5	$8.72	9.138%	$9.5168	$9.52	$9.50	$9.50
Purchase #6	$215.78	7.467%	$231.8923	$231.89	$231.90	$231.90
Purchase #7	$247.75	12.675%	$279.1523	$279.15	$279.15	$279.20
7 purchase totals =	$929.78		$1,014.2957	$1,014.29	$1,014.25	$1,014.30