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	$162.93	12.213%	$182.8286	$182.83	$182.85	$182.80
Purchase #2	$79.70	13.526%	$90.4802	$90.48	$90.50	$90.50
Purchase #3	$180.70	4.356%	$188.5713	$188.57	$188.55	$188.60
Purchase #4	$102.85	9.543%	$112.665	$112.67	$112.65	$112.70
Purchase #5	$142.50	7.641%	$153.3884	$153.39	$153.40	$153.40
Purchase #6	$244.38	9.547%	$267.711	$267.71	$267.70	$267.70
Purchase #7	$95.64	10.696%	$105.8697	$105.87	$105.85	$105.90
7 purchase totals =	$1,008.70		$1,101.5142	$1,101.52	$1,101.50	$1,101.60