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	$181.94	7.737%	$196.0167	$196.02	$196.00	$196.00
Purchase #2	$19.90	6.765%	$21.2462	$21.25	$21.25	$21.20
Purchase #3	$46.57	9.608%	$51.0444	$51.04	$51.05	$51.00
Purchase #4	$200.25	4.691%	$209.6437	$209.64	$209.65	$209.60
Purchase #5	$182.62	13.544%	$207.3541	$207.35	$207.35	$207.40
Purchase #6	$165.88	4.607%	$173.5221	$173.52	$173.50	$173.50
Purchase #7	$151.40	4.303%	$157.9147	$157.91	$157.90	$157.90
7 purchase totals =	$948.56		$1,016.7419	$1,016.73	$1,016.70	$1,016.60