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	$237.75	11.678%	$265.5144	$265.51	$265.50	$265.50
Purchase #2	$102.75	6.407%	$109.3332	$109.33	$109.35	$109.30
Purchase #3	$77.48	3.108%	$79.8881	$79.89	$79.90	$79.90
Purchase #4	$74.85	11.115%	$83.1696	$83.17	$83.15	$83.20
Purchase #5	$168.59	13.178%	$190.8068	$190.81	$190.80	$190.80
Purchase #6	$213.93	9.552%	$234.3646	$234.36	$234.35	$234.40
Purchase #7	$59.43	4.644%	$62.1899	$62.19	$62.20	$62.20
7 purchase totals =	$934.78		$1,025.2666	$1,025.26	$1,025.25	$1,025.30