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	$147.25	7.349%	$158.0714	$158.07	$158.05	$158.10
Purchase #2	$29.29	8.551%	$31.7946	$31.79	$31.80	$31.80
Purchase #3	$88.79	7.131%	$95.1216	$95.12	$95.10	$95.10
Purchase #4	$35.53	12.635%	$40.0192	$40.02	$40.00	$40.00
Purchase #5	$219.96	3.549%	$227.7664	$227.77	$227.75	$227.80
Purchase #6	$62.54	6.141%	$66.3806	$66.38	$66.40	$66.40
Purchase #7	$98.92	6.499%	$105.3488	$105.35	$105.35	$105.30
7 purchase totals =	$682.28		$724.5026	$724.50	$724.45	$724.50