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	$58.82	6.319%	$62.5368	$62.54	$62.55	$62.50
Purchase #2	$30.35	9.797%	$33.3234	$33.32	$33.30	$33.30
Purchase #3	$14.86	10.264%	$16.3852	$16.39	$16.40	$16.40
Purchase #4	$42.41	7.685%	$45.6692	$45.67	$45.65	$45.70
Purchase #5	$19.33	10.125%	$21.2872	$21.29	$21.30	$21.30
Purchase #6	$224.82	7.230%	$241.0745	$241.07	$241.05	$241.10
Purchase #7	$43.30	7.644%	$46.6099	$46.61	$46.60	$46.60
7 purchase totals =	$433.89		$466.8862	$466.89	$466.85	$466.90