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	$207.59	8.314%	$224.849	$224.85	$224.85	$224.80
Purchase #2	$224.77	6.512%	$239.407	$239.41	$239.40	$239.40
Purchase #3	$59.53	3.375%	$61.5391	$61.54	$61.55	$61.50
Purchase #4	$237.46	6.771%	$253.5384	$253.54	$253.55	$253.50
Purchase #5	$89.63	11.775%	$100.1839	$100.18	$100.20	$100.20
Purchase #6	$162.96	12.638%	$183.5549	$183.55	$183.55	$183.60
Purchase #7	$74.29	9.551%	$81.3854	$81.39	$81.40	$81.40
7 purchase totals =	$1,056.23		$1,144.4577	$1,144.46	$1,144.50	$1,144.40