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	$104.75	7.722%	$112.8388	$112.84	$112.85	$112.80
Purchase #2	$229.85	11.161%	$255.5036	$255.50	$255.50	$255.50
Purchase #3	$160.81	7.343%	$172.6183	$172.62	$172.60	$172.60
Purchase #4	$31.55	3.141%	$32.541	$32.54	$32.55	$32.50
Purchase #5	$113.74	9.217%	$124.2234	$124.22	$124.20	$124.20
Purchase #6	$170.40	7.128%	$182.5461	$182.55	$182.55	$182.50
Purchase #7	$191.63	7.402%	$205.8145	$205.81	$205.80	$205.80
7 purchase totals =	$1,002.73		$1,086.0857	$1,086.08	$1,086.05	$1,085.90