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	$183.98	11.445%	$205.0365	$205.04	$205.05	$205.00
Purchase #2	$216.66	4.798%	$227.0553	$227.06	$227.05	$227.10
Purchase #3	$26.36	11.736%	$29.4536	$29.45	$29.45	$29.50
Purchase #4	$205.60	5.607%	$217.128	$217.13	$217.15	$217.10
Purchase #5	$205.54	8.396%	$222.7971	$222.80	$222.80	$222.80
Purchase #6	$82.78	7.388%	$88.8958	$88.90	$88.90	$88.90
Purchase #7	$164.54	4.410%	$171.7962	$171.80	$171.80	$171.80
7 purchase totals =	$1,085.46		$1,162.1625	$1,162.18	$1,162.20	$1,162.20