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	$171.86	13.767%	$195.52	$195.52	$195.50	$195.50
Purchase #2	$94.39	13.287%	$106.9316	$106.93	$106.95	$106.90
Purchase #3	$144.66	10.275%	$159.5238	$159.52	$159.50	$159.50
Purchase #4	$209.46	11.381%	$233.2986	$233.30	$233.30	$233.30
Purchase #5	$19.84	4.757%	$20.7838	$20.78	$20.80	$20.80
Purchase #6	$175.89	7.318%	$188.7616	$188.76	$188.75	$188.80
Purchase #7	$102.85	3.629%	$106.5824	$106.58	$106.60	$106.60
7 purchase totals =	$918.95		$1,011.4018	$1,011.39	$1,011.40	$1,011.40