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	$95.97	9.852%	$105.425	$105.43	$105.45	$105.40
Purchase #2	$48.97	10.790%	$54.2539	$54.25	$54.25	$54.30
Purchase #3	$223.48	3.680%	$231.7041	$231.70	$231.70	$231.70
Purchase #4	$92.47	5.835%	$97.8656	$97.87	$97.85	$97.90
Purchase #5	$72.84	7.251%	$78.1216	$78.12	$78.10	$78.10
Purchase #6	$236.81	10.860%	$262.5276	$262.53	$262.55	$262.50
Purchase #7	$205.48	3.660%	$213.0006	$213.00	$213.00	$213.00
7 purchase totals =	$976.02		$1,042.8984	$1,042.90	$1,042.90	$1,042.90