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	$236.46	11.110%	$262.7307	$262.73	$262.75	$262.70
Purchase #2	$33.32	3.704%	$34.5542	$34.55	$34.55	$34.60
Purchase #3	$87.96	9.615%	$96.4174	$96.42	$96.40	$96.40
Purchase #4	$59.61	13.764%	$67.8147	$67.81	$67.80	$67.80
Purchase #5	$166.82	5.435%	$175.8867	$175.89	$175.90	$175.90
Purchase #6	$208.90	13.404%	$236.901	$236.90	$236.90	$236.90
Purchase #7	$151.80	10.398%	$167.5842	$167.58	$167.60	$167.60
7 purchase totals =	$944.87		$1,041.8889	$1,041.88	$1,041.90	$1,041.90