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	$67.96	7.816%	$73.2718	$73.27	$73.25	$73.30
Purchase #2	$70.31	4.839%	$73.7123	$73.71	$73.70	$73.70
Purchase #3	$225.77	9.522%	$247.2678	$247.27	$247.25	$247.30
Purchase #4	$95.75	10.133%	$105.4523	$105.45	$105.45	$105.50
Purchase #5	$210.88	7.704%	$227.1262	$227.13	$227.15	$227.10
Purchase #6	$157.64	6.721%	$168.235	$168.24	$168.25	$168.20
Purchase #7	$148.79	11.482%	$165.8741	$165.87	$165.85	$165.90
7 purchase totals =	$977.10		$1,060.9395	$1,060.94	$1,060.90	$1,061.00