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	$190.47	11.740%	$212.8312	$212.83	$212.85	$212.80
Purchase #2	$215.43	11.632%	$240.4888	$240.49	$240.50	$240.50
Purchase #3	$53.76	7.615%	$57.8538	$57.85	$57.85	$57.90
Purchase #4	$85.89	8.619%	$93.2929	$93.29	$93.30	$93.30
Purchase #5	$130.50	8.858%	$142.0597	$142.06	$142.05	$142.10
Purchase #6	$92.73	7.559%	$99.7395	$99.74	$99.75	$99.70
Purchase #7	$99.66	9.537%	$109.1646	$109.16	$109.15	$109.20
7 purchase totals =	$868.44		$955.4305	$955.42	$955.45	$955.50