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	$148.79	7.563%	$160.043	$160.04	$160.05	$160.00
Purchase #2	$52.76	12.538%	$59.375	$59.38	$59.40	$59.40
Purchase #3	$117.80	5.156%	$123.8738	$123.87	$123.85	$123.90
Purchase #4	$113.45	7.159%	$121.5719	$121.57	$121.55	$121.60
Purchase #5	$161.93	8.310%	$175.3864	$175.39	$175.40	$175.40
Purchase #6	$180.94	4.256%	$188.6408	$188.64	$188.65	$188.60
Purchase #7	$166.98	9.860%	$183.4442	$183.44	$183.45	$183.40
7 purchase totals =	$942.65		$1,012.3351	$1,012.33	$1,012.35	$1,012.30