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	$168.96	3.219%	$174.3988	$174.40	$174.40	$174.40
Purchase #2	$177.60	10.832%	$196.8376	$196.84	$196.85	$196.80
Purchase #3	$83.82	7.835%	$90.3873	$90.39	$90.40	$90.40
Purchase #4	$67.72	8.243%	$73.3022	$73.30	$73.30	$73.30
Purchase #5	$21.38	12.164%	$23.9807	$23.98	$24.00	$24.00
Purchase #6	$166.27	8.127%	$179.7828	$179.78	$179.80	$179.80
Purchase #7	$246.98	7.578%	$265.6961	$265.70	$265.70	$265.70
7 purchase totals =	$932.73		$1,004.3855	$1,004.39	$1,004.45	$1,004.40