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	$186.64	13.527%	$211.8868	$211.89	$211.90	$211.90
Purchase #2	$182.49	7.419%	$196.0289	$196.03	$196.05	$196.00
Purchase #3	$177.50	4.144%	$184.8556	$184.86	$184.85	$184.90
Purchase #4	$120.79	13.481%	$137.0737	$137.07	$137.05	$137.10
Purchase #5	$163.59	13.797%	$186.1605	$186.16	$186.15	$186.20
Purchase #6	$113.82	8.618%	$123.629	$123.63	$123.65	$123.60
Purchase #7	$48.47	11.232%	$53.9142	$53.91	$53.90	$53.90
7 purchase totals =	$993.30		$1,093.5487	$1,093.55	$1,093.55	$1,093.60