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	$119.48	11.815%	$133.5966	$133.60	$133.60	$133.60
Purchase #2	$57.71	5.264%	$60.7479	$60.75	$60.75	$60.70
Purchase #3	$95.79	13.829%	$109.0368	$109.04	$109.05	$109.00
Purchase #4	$124.98	13.452%	$141.7923	$141.79	$141.80	$141.80
Purchase #5	$98.83	13.714%	$112.3835	$112.38	$112.40	$112.40
Purchase #6	$72.65	13.581%	$82.5166	$82.52	$82.50	$82.50
Purchase #7	$117.45	11.517%	$130.9767	$130.98	$131.00	$131.00
7 purchase totals =	$686.89		$771.0504	$771.06	$771.10	$771.00