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	$175.32	11.591%	$195.6413	$195.64	$195.65	$195.60
Purchase #2	$234.73	13.274%	$265.8881	$265.89	$265.90	$265.90
Purchase #3	$29.46	12.338%	$33.0948	$33.09	$33.10	$33.10
Purchase #4	$108.62	4.654%	$113.6752	$113.68	$113.70	$113.70
Purchase #5	$110.72	11.852%	$123.8425	$123.84	$123.85	$123.80
Purchase #6	$77.93	7.705%	$83.9345	$83.93	$83.95	$83.90
Purchase #7	$233.96	13.386%	$265.2779	$265.28	$265.30	$265.30
7 purchase totals =	$970.74		$1,081.3543	$1,081.35	$1,081.45	$1,081.30