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	$148.82	3.185%	$153.5599	$153.56	$153.55	$153.60
Purchase #2	$207.46	5.374%	$218.6089	$218.61	$218.60	$218.60
Purchase #3	$103.33	10.271%	$113.943	$113.94	$113.95	$113.90
Purchase #4	$231.60	8.502%	$251.2906	$251.29	$251.30	$251.30
Purchase #5	$153.38	10.480%	$169.4542	$169.45	$169.45	$169.50
Purchase #6	$81.69	7.690%	$87.972	$87.97	$87.95	$88.00
Purchase #7	$20.53	5.114%	$21.5799	$21.58	$21.60	$21.60
7 purchase totals =	$946.81		$1,016.4085	$1,016.40	$1,016.40	$1,016.50