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	$98.85	8.794%	$107.5429	$107.54	$107.55	$107.50
Purchase #2	$151.69	7.140%	$162.5207	$162.52	$162.50	$162.50
Purchase #3	$107.79	4.701%	$112.8572	$112.86	$112.85	$112.90
Purchase #4	$181.53	13.309%	$205.6898	$205.69	$205.70	$205.70
Purchase #5	$228.84	10.799%	$253.5524	$253.55	$253.55	$253.60
Purchase #6	$106.26	9.238%	$116.0763	$116.08	$116.10	$116.10
Purchase #7	$90.48	6.753%	$96.5901	$96.59	$96.60	$96.60
7 purchase totals =	$965.44		$1,054.8294	$1,054.83	$1,054.85	$1,054.90