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	$56.49	10.567%	$62.4593	$62.46	$62.45	$62.50
Purchase #2	$39.98	11.110%	$44.4218	$44.42	$44.40	$44.40
Purchase #3	$98.91	13.253%	$112.0185	$112.02	$112.00	$112.00
Purchase #4	$59.30	5.873%	$62.7827	$62.78	$62.80	$62.80
Purchase #5	$110.79	11.281%	$123.2882	$123.29	$123.30	$123.30
Purchase #6	$96.83	4.228%	$100.924	$100.92	$100.90	$100.90
Purchase #7	$207.28	4.276%	$216.1433	$216.14	$216.15	$216.10
7 purchase totals =	$669.58		$722.0378	$722.03	$722.00	$722.00