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	$195.59	7.522%	$210.3023	$210.30	$210.30	$210.30
Purchase #2	$93.75	8.254%	$101.4881	$101.49	$101.50	$101.50
Purchase #3	$94.94	4.808%	$99.5047	$99.50	$99.50	$99.50
Purchase #4	$71.98	8.782%	$78.3013	$78.30	$78.30	$78.30
Purchase #5	$127.64	7.772%	$137.5602	$137.56	$137.55	$137.60
Purchase #6	$61.94	5.497%	$65.3448	$65.34	$65.35	$65.30
Purchase #7	$107.42	5.379%	$113.1981	$113.20	$113.20	$113.20
7 purchase totals =	$753.26		$805.6995	$805.69	$805.70	$805.70