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	$187.97	4.352%	$196.1505	$196.15	$196.15	$196.20
Purchase #2	$40.63	4.703%	$42.5408	$42.54	$42.55	$42.50
Purchase #3	$210.50	11.322%	$234.3328	$234.33	$234.35	$234.30
Purchase #4	$82.55	12.359%	$92.7524	$92.75	$92.75	$92.80
Purchase #5	$141.99	3.622%	$147.1329	$147.13	$147.15	$147.10
Purchase #6	$46.83	11.241%	$52.0942	$52.09	$52.10	$52.10
Purchase #7	$138.66	7.439%	$148.9749	$148.97	$148.95	$149.00
7 purchase totals =	$849.13		$913.9785	$913.96	$914.00	$914.00