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	$151.39	7.185%	$162.2674	$162.27	$162.25	$162.30
Purchase #2	$62.59	13.265%	$70.8926	$70.89	$70.90	$70.90
Purchase #3	$181.35	10.669%	$200.6982	$200.70	$200.70	$200.70
Purchase #4	$90.87	4.584%	$95.0355	$95.04	$95.05	$95.00
Purchase #5	$130.75	8.471%	$141.8258	$141.83	$141.85	$141.80
Purchase #6	$243.25	6.102%	$258.0931	$258.09	$258.10	$258.10
Purchase #7	$113.56	10.727%	$125.7416	$125.74	$125.75	$125.70
7 purchase totals =	$973.76		$1,054.5542	$1,054.56	$1,054.60	$1,054.50