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	$134.80	5.776%	$142.586	$142.59	$142.60	$142.60
Purchase #2	$29.57	6.396%	$31.4613	$31.46	$31.45	$31.50
Purchase #3	$135.97	12.398%	$152.8276	$152.83	$152.85	$152.80
Purchase #4	$180.90	13.654%	$205.6001	$205.60	$205.60	$205.60
Purchase #5	$223.50	10.820%	$247.6827	$247.68	$247.70	$247.70
Purchase #6	$227.74	8.686%	$247.5215	$247.52	$247.50	$247.50
Purchase #7	$158.27	5.608%	$167.1458	$167.15	$167.15	$167.10
7 purchase totals =	$1,090.75		$1,194.8250	$1,194.83	$1,194.85	$1,194.80