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	$167.82	4.611%	$175.5582	$175.56	$175.55	$175.60
Purchase #2	$156.92	6.580%	$167.2453	$167.25	$167.25	$167.20
Purchase #3	$213.96	4.157%	$222.8543	$222.85	$222.85	$222.90
Purchase #4	$185.38	13.163%	$209.7816	$209.78	$209.80	$209.80
Purchase #5	$217.66	8.784%	$236.7793	$236.78	$236.80	$236.80
Purchase #6	$78.96	10.539%	$87.2816	$87.28	$87.30	$87.30
Purchase #7	$155.41	11.250%	$172.8936	$172.89	$172.90	$172.90
7 purchase totals =	$1,176.11		$1,272.3939	$1,272.39	$1,272.45	$1,272.50