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	$163.60	13.561%	$185.7858	$185.79	$185.80	$185.80
Purchase #2	$191.59	4.130%	$199.5027	$199.50	$199.50	$199.50
Purchase #3	$123.59	6.402%	$131.5022	$131.50	$131.50	$131.50
Purchase #4	$14.73	13.759%	$16.7567	$16.76	$16.75	$16.80
Purchase #5	$68.84	12.545%	$77.476	$77.48	$77.50	$77.50
Purchase #6	$171.84	9.719%	$188.5411	$188.54	$188.55	$188.50
Purchase #7	$209.71	12.849%	$236.6556	$236.66	$236.65	$236.70
7 purchase totals =	$943.90		$1,036.2201	$1,036.23	$1,036.25	$1,036.30