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	$196.55	10.605%	$217.3941	$217.39	$217.40	$217.40
Purchase #2	$39.51	8.609%	$42.9114	$42.91	$42.90	$42.90
Purchase #3	$87.86	11.738%	$98.173	$98.17	$98.15	$98.20
Purchase #4	$53.53	8.176%	$57.9066	$57.91	$57.90	$57.90
Purchase #5	$86.51	10.494%	$95.5884	$95.59	$95.60	$95.60
Purchase #6	$18.59	5.597%	$19.6305	$19.63	$19.65	$19.60
Purchase #7	$208.78	5.636%	$220.5468	$220.55	$220.55	$220.50
7 purchase totals =	$691.33		$752.1508	$752.15	$752.15	$752.10