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	$195.25	4.680%	$204.3877	$204.39	$204.40	$204.40
Purchase #2	$20.56	9.411%	$22.4949	$22.49	$22.50	$22.50
Purchase #3	$87.80	6.413%	$93.4306	$93.43	$93.45	$93.40
Purchase #4	$116.89	12.159%	$131.1027	$131.10	$131.10	$131.10
Purchase #5	$233.41	13.412%	$264.7149	$264.71	$264.70	$264.70
Purchase #6	$207.32	7.266%	$222.3839	$222.38	$222.40	$222.40
Purchase #7	$200.34	11.780%	$223.9401	$223.94	$223.95	$223.90
7 purchase totals =	$1,061.57		$1,162.4548	$1,162.44	$1,162.50	$1,162.40