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	$196.62	11.572%	$219.3729	$219.37	$219.35	$219.40
Purchase #2	$185.46	11.585%	$206.9455	$206.95	$206.95	$206.90
Purchase #3	$51.58	7.585%	$55.4923	$55.49	$55.50	$55.50
Purchase #4	$88.56	13.598%	$100.6024	$100.60	$100.60	$100.60
Purchase #5	$241.78	9.223%	$264.0794	$264.08	$264.10	$264.10
Purchase #6	$100.60	13.413%	$114.0935	$114.09	$114.10	$114.10
Purchase #7	$55.41	13.577%	$62.933	$62.93	$62.95	$62.90
7 purchase totals =	$920.01		$1,023.5190	$1,023.51	$1,023.55	$1,023.50