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	$242.54	9.500%	$265.5813	$265.58	$265.60	$265.60
Purchase #2	$82.31	4.140%	$85.7176	$85.72	$85.70	$85.70
Purchase #3	$39.41	6.336%	$41.907	$41.91	$41.90	$41.90
Purchase #4	$115.93	12.348%	$130.245	$130.25	$130.25	$130.20
Purchase #5	$178.27	12.204%	$200.0261	$200.03	$200.05	$200.00
Purchase #6	$166.46	10.267%	$183.5504	$183.55	$183.55	$183.60
Purchase #7	$173.86	8.193%	$188.1043	$188.10	$188.10	$188.10
7 purchase totals =	$998.78		$1,095.1317	$1,095.14	$1,095.15	$1,095.10