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	$141.31	7.802%	$152.335	$152.34	$152.35	$152.30
Purchase #2	$33.42	7.433%	$35.9041	$35.90	$35.90	$35.90
Purchase #3	$59.80	3.467%	$61.8733	$61.87	$61.85	$61.90
Purchase #4	$197.82	4.119%	$205.9682	$205.97	$205.95	$206.00
Purchase #5	$242.62	9.368%	$265.3486	$265.35	$265.35	$265.30
Purchase #6	$138.60	12.171%	$155.469	$155.47	$155.45	$155.50
Purchase #7	$24.91	10.338%	$27.4852	$27.49	$27.50	$27.50
7 purchase totals =	$838.48		$904.3834	$904.39	$904.35	$904.40