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	$82.62	13.746%	$93.9769	$93.98	$94.00	$94.00
Purchase #2	$232.80	11.473%	$259.5091	$259.51	$259.50	$259.50
Purchase #3	$144.46	4.826%	$151.4316	$151.43	$151.45	$151.40
Purchase #4	$244.94	11.640%	$273.451	$273.45	$273.45	$273.50
Purchase #5	$127.40	4.144%	$132.6795	$132.68	$132.70	$132.70
Purchase #6	$106.74	5.767%	$112.8957	$112.90	$112.90	$112.90
Purchase #7	$118.50	8.812%	$128.9422	$128.94	$128.95	$128.90
7 purchase totals =	$1,057.46		$1,152.8860	$1,152.89	$1,152.95	$1,152.90