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	$57.31	4.830%	$60.0781	$60.08	$60.10	$60.10
Purchase #2	$138.61	11.149%	$154.0636	$154.06	$154.05	$154.10
Purchase #3	$164.89	4.557%	$172.404	$172.40	$172.40	$172.40
Purchase #4	$128.72	3.166%	$132.7953	$132.80	$132.80	$132.80
Purchase #5	$38.80	8.793%	$42.2117	$42.21	$42.20	$42.20
Purchase #6	$208.66	4.768%	$218.6089	$218.61	$218.60	$218.60
Purchase #7	$220.42	11.115%	$244.9197	$244.92	$244.90	$244.90
7 purchase totals =	$957.41		$1,025.0813	$1,025.08	$1,025.05	$1,025.10