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	$184.30	13.615%	$209.3924	$209.39	$209.40	$209.40
Purchase #2	$148.82	11.813%	$166.4001	$166.40	$166.40	$166.40
Purchase #3	$32.56	13.773%	$37.0445	$37.04	$37.05	$37.00
Purchase #4	$213.29	4.263%	$222.3826	$222.38	$222.40	$222.40
Purchase #5	$154.37	6.200%	$163.9409	$163.94	$163.95	$163.90
Purchase #6	$220.59	3.555%	$228.432	$228.43	$228.45	$228.40
Purchase #7	$28.36	12.651%	$31.9478	$31.95	$31.95	$31.90
7 purchase totals =	$982.29		$1,059.5403	$1,059.53	$1,059.60	$1,059.40