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	$103.25	8.418%	$111.9416	$111.94	$111.95	$111.90
Purchase #2	$176.54	5.606%	$186.4368	$186.44	$186.45	$186.40
Purchase #3	$89.68	5.861%	$94.9361	$94.94	$94.95	$94.90
Purchase #4	$170.98	13.806%	$194.5855	$194.59	$194.60	$194.60
Purchase #5	$54.54	13.628%	$61.9727	$61.97	$61.95	$62.00
Purchase #6	$42.79	8.412%	$46.3895	$46.39	$46.40	$46.40
Purchase #7	$177.64	11.527%	$198.1166	$198.12	$198.10	$198.10
7 purchase totals =	$815.42		$894.3788	$894.39	$894.40	$894.30