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	$82.75	13.872%	$94.2291	$94.23	$94.25	$94.20
Purchase #2	$62.28	8.238%	$67.4106	$67.41	$67.40	$67.40
Purchase #3	$225.56	5.557%	$238.0944	$238.09	$238.10	$238.10
Purchase #4	$208.57	5.438%	$219.912	$219.91	$219.90	$219.90
Purchase #5	$202.65	6.794%	$216.418	$216.42	$216.40	$216.40
Purchase #6	$120.42	5.362%	$126.8769	$126.88	$126.90	$126.90
Purchase #7	$111.71	6.149%	$118.579	$118.58	$118.60	$118.60
7 purchase totals =	$1,013.94		$1,081.5200	$1,081.52	$1,081.55	$1,081.50