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	$69.44	9.411%	$75.975	$75.98	$76.00	$76.00
Purchase #2	$21.69	9.448%	$23.7393	$23.74	$23.75	$23.70
Purchase #3	$74.94	11.269%	$83.385	$83.39	$83.40	$83.40
Purchase #4	$27.81	13.686%	$31.6161	$31.62	$31.60	$31.60
Purchase #5	$237.60	10.272%	$262.0063	$262.01	$262.00	$262.00
Purchase #6	$115.60	6.561%	$123.1845	$123.18	$123.20	$123.20
Purchase #7	$61.67	9.648%	$67.6199	$67.62	$67.60	$67.60
7 purchase totals =	$608.75		$667.5261	$667.54	$667.55	$667.50