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	$68.30	6.774%	$72.9266	$72.93	$72.95	$72.90
Purchase #2	$58.88	7.792%	$63.4679	$63.47	$63.45	$63.50
Purchase #3	$132.72	10.514%	$146.6742	$146.67	$146.65	$146.70
Purchase #4	$141.83	9.668%	$155.5421	$155.54	$155.55	$155.50
Purchase #5	$187.94	11.559%	$209.664	$209.66	$209.65	$209.70
Purchase #6	$193.38	6.839%	$206.6053	$206.61	$206.60	$206.60
Purchase #7	$181.80	8.218%	$196.7403	$196.74	$196.75	$196.70
7 purchase totals =	$964.85		$1,051.6204	$1,051.62	$1,051.60	$1,051.60