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	$148.67	5.564%	$156.942	$156.94	$156.95	$156.90
Purchase #2	$20.57	4.332%	$21.4611	$21.46	$21.45	$21.50
Purchase #3	$19.60	5.633%	$20.7041	$20.70	$20.70	$20.70
Purchase #4	$109.25	9.154%	$119.2507	$119.25	$119.25	$119.30
Purchase #5	$133.40	9.674%	$146.3051	$146.31	$146.30	$146.30
Purchase #6	$170.29	5.296%	$179.3086	$179.31	$179.30	$179.30
Purchase #7	$74.71	5.141%	$78.5508	$78.55	$78.55	$78.60
7 purchase totals =	$676.49		$722.5224	$722.52	$722.50	$722.60