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	$188.32	11.555%	$210.0804	$210.08	$210.10	$210.10
Purchase #2	$94.34	3.209%	$97.3674	$97.37	$97.35	$97.40
Purchase #3	$155.72	4.428%	$162.6153	$162.62	$162.60	$162.60
Purchase #4	$137.34	4.786%	$143.9131	$143.91	$143.90	$143.90
Purchase #5	$98.94	4.448%	$103.3409	$103.34	$103.35	$103.30
Purchase #6	$144.33	12.821%	$162.8345	$162.83	$162.85	$162.80
Purchase #7	$167.67	7.564%	$180.3526	$180.35	$180.35	$180.40
7 purchase totals =	$986.66		$1,060.5042	$1,060.50	$1,060.50	$1,060.50