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	$198.42	13.812%	$225.8258	$225.83	$225.85	$225.80
Purchase #2	$188.52	3.714%	$195.5216	$195.52	$195.50	$195.50
Purchase #3	$126.86	4.223%	$132.2173	$132.22	$132.20	$132.20
Purchase #4	$179.41	9.320%	$196.131	$196.13	$196.15	$196.10
Purchase #5	$58.67	13.445%	$66.5582	$66.56	$66.55	$66.60
Purchase #6	$168.74	11.741%	$188.5518	$188.55	$188.55	$188.60
Purchase #7	$41.77	6.724%	$44.5786	$44.58	$44.60	$44.60
7 purchase totals =	$962.39		$1,049.3843	$1,049.39	$1,049.40	$1,049.40