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	$226.73	6.326%	$241.0729	$241.07	$241.05	$241.10
Purchase #2	$151.32	13.550%	$171.8239	$171.82	$171.80	$171.80
Purchase #3	$92.35	3.471%	$95.5555	$95.56	$95.55	$95.60
Purchase #4	$209.90	5.768%	$222.007	$222.01	$222.00	$222.00
Purchase #5	$141.73	7.425%	$152.2535	$152.25	$152.25	$152.30
Purchase #6	$73.43	5.710%	$77.6229	$77.62	$77.60	$77.60
Purchase #7	$182.73	4.849%	$191.5906	$191.59	$191.60	$191.60
7 purchase totals =	$1,078.19		$1,151.9263	$1,151.92	$1,151.85	$1,152.00