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	$60.37	3.841%	$62.6888	$62.69	$62.70	$62.70
Purchase #2	$113.96	12.540%	$128.2506	$128.25	$128.25	$128.30
Purchase #3	$248.39	13.578%	$282.1164	$282.12	$282.10	$282.10
Purchase #4	$51.72	13.746%	$58.8294	$58.83	$58.85	$58.80
Purchase #5	$89.47	6.503%	$95.2882	$95.29	$95.30	$95.30
Purchase #6	$109.34	6.133%	$116.0458	$116.05	$116.05	$116.00
Purchase #7	$24.40	11.768%	$27.2714	$27.27	$27.25	$27.30
7 purchase totals =	$697.65		$770.4906	$770.50	$770.50	$770.50