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	$190.85	11.275%	$212.3683	$212.37	$212.35	$212.40
Purchase #2	$84.41	11.454%	$94.0783	$94.08	$94.10	$94.10
Purchase #3	$174.64	12.292%	$196.1067	$196.11	$196.10	$196.10
Purchase #4	$154.33	5.509%	$162.832	$162.83	$162.85	$162.80
Purchase #5	$159.53	10.713%	$176.6204	$176.62	$176.60	$176.60
Purchase #6	$58.58	7.278%	$62.8435	$62.84	$62.85	$62.80
Purchase #7	$120.42	5.659%	$127.2346	$127.23	$127.25	$127.20
7 purchase totals =	$942.76		$1,032.0838	$1,032.08	$1,032.10	$1,032.00