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	$95.40	10.815%	$105.7175	$105.72	$105.70	$105.70
Purchase #2	$231.64	5.206%	$243.6992	$243.70	$243.70	$243.70
Purchase #3	$120.70	5.482%	$127.3168	$127.32	$127.30	$127.30
Purchase #4	$151.82	9.815%	$166.7211	$166.72	$166.70	$166.70
Purchase #5	$100.45	9.377%	$109.8692	$109.87	$109.85	$109.90
Purchase #6	$104.26	3.629%	$108.0436	$108.04	$108.05	$108.00
Purchase #7	$174.74	10.108%	$192.4027	$192.40	$192.40	$192.40
7 purchase totals =	$979.01		$1,053.7701	$1,053.77	$1,053.70	$1,053.70