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	$92.85	13.498%	$105.3829	$105.38	$105.40	$105.40
Purchase #2	$34.28	13.784%	$39.0052	$39.01	$39.00	$39.00
Purchase #3	$172.84	10.395%	$190.8067	$190.81	$190.80	$190.80
Purchase #4	$83.59	10.418%	$92.2984	$92.30	$92.30	$92.30
Purchase #5	$171.97	5.758%	$181.872	$181.87	$181.85	$181.90
Purchase #6	$152.89	8.153%	$165.3551	$165.36	$165.35	$165.40
Purchase #7	$222.41	7.682%	$239.4955	$239.50	$239.50	$239.50
7 purchase totals =	$930.83		$1,014.2158	$1,014.23	$1,014.20	$1,014.30