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	$162.58	12.445%	$182.8131	$182.81	$182.80	$182.80
Purchase #2	$210.26	5.761%	$222.3731	$222.37	$222.35	$222.40
Purchase #3	$65.77	7.570%	$70.7488	$70.75	$70.75	$70.70
Purchase #4	$219.38	10.528%	$242.4763	$242.48	$242.50	$242.50
Purchase #5	$232.82	11.209%	$258.9168	$258.92	$258.90	$258.90
Purchase #6	$25.52	13.525%	$28.9716	$28.97	$28.95	$29.00
Purchase #7	$47.89	12.453%	$53.8537	$53.85	$53.85	$53.90
7 purchase totals =	$964.22		$1,060.1534	$1,060.15	$1,060.10	$1,060.20