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	$185.79	10.784%	$205.8256	$205.83	$205.85	$205.80
Purchase #2	$12.74	6.514%	$13.5699	$13.57	$13.55	$13.60
Purchase #3	$177.66	8.142%	$192.1251	$192.13	$192.15	$192.10
Purchase #4	$142.91	9.729%	$156.8137	$156.81	$156.80	$156.80
Purchase #5	$146.66	10.575%	$162.1693	$162.17	$162.15	$162.20
Purchase #6	$94.78	12.417%	$106.5488	$106.55	$106.55	$106.50
Purchase #7	$238.90	7.515%	$256.8533	$256.85	$256.85	$256.90
7 purchase totals =	$999.44		$1,093.9057	$1,093.91	$1,093.90	$1,093.90