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	$216.86	9.641%	$237.7675	$237.77	$237.75	$237.80
Purchase #2	$247.56	12.608%	$278.7724	$278.77	$278.75	$278.80
Purchase #3	$41.44	9.646%	$45.4373	$45.44	$45.45	$45.40
Purchase #4	$140.73	13.617%	$159.8932	$159.89	$159.90	$159.90
Purchase #5	$231.91	10.745%	$256.8287	$256.83	$256.85	$256.80
Purchase #6	$31.43	7.277%	$33.7172	$33.72	$33.70	$33.70
Purchase #7	$43.29	7.622%	$46.5896	$46.59	$46.60	$46.60
7 purchase totals =	$953.22		$1,059.0059	$1,059.01	$1,059.00	$1,059.00