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	$78.87	8.854%	$85.8531	$85.85	$85.85	$85.90
Purchase #2	$195.71	6.592%	$208.6112	$208.61	$208.60	$208.60
Purchase #3	$128.79	3.178%	$132.8829	$132.88	$132.90	$132.90
Purchase #4	$190.52	8.209%	$206.1598	$206.16	$206.15	$206.20
Purchase #5	$207.56	8.654%	$225.5222	$225.52	$225.50	$225.50
Purchase #6	$53.87	3.197%	$55.5922	$55.59	$55.60	$55.60
Purchase #7	$96.80	13.564%	$109.93	$109.93	$109.95	$109.90
7 purchase totals =	$952.12		$1,024.5514	$1,024.54	$1,024.55	$1,024.60