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	$209.28	7.210%	$224.3691	$224.37	$224.35	$224.40
Purchase #2	$130.98	10.177%	$144.3098	$144.31	$144.30	$144.30
Purchase #3	$41.50	3.336%	$42.8844	$42.88	$42.90	$42.90
Purchase #4	$112.95	6.611%	$120.4171	$120.42	$120.40	$120.40
Purchase #5	$215.55	5.541%	$227.4936	$227.49	$227.50	$227.50
Purchase #6	$160.84	4.825%	$168.6005	$168.60	$168.60	$168.60
Purchase #7	$183.73	4.436%	$191.8803	$191.88	$191.90	$191.90
7 purchase totals =	$1,054.83		$1,119.9548	$1,119.95	$1,119.95	$1,120.00