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	$213.39	4.462%	$222.9115	$222.91	$222.90	$222.90
Purchase #2	$202.53	5.241%	$213.1446	$213.14	$213.15	$213.10
Purchase #3	$69.79	8.345%	$75.614	$75.61	$75.60	$75.60
Purchase #4	$66.77	8.470%	$72.4254	$72.43	$72.45	$72.40
Purchase #5	$139.28	8.358%	$150.921	$150.92	$150.90	$150.90
Purchase #6	$198.60	13.104%	$224.6245	$224.62	$224.60	$224.60
Purchase #7	$196.42	6.683%	$209.5467	$209.55	$209.55	$209.50
7 purchase totals =	$1,086.78		$1,169.1877	$1,169.18	$1,169.15	$1,169.00