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	$32.80	7.708%	$35.3282	$35.33	$35.35	$35.30
Purchase #2	$69.30	13.595%	$78.7213	$78.72	$78.70	$78.70
Purchase #3	$224.32	7.707%	$241.6083	$241.61	$241.60	$241.60
Purchase #4	$57.79	8.558%	$62.7357	$62.74	$62.75	$62.70
Purchase #5	$181.57	8.345%	$196.722	$196.72	$196.70	$196.70
Purchase #6	$206.72	12.808%	$233.1967	$233.20	$233.20	$233.20
Purchase #7	$190.97	10.648%	$211.3045	$211.30	$211.30	$211.30
7 purchase totals =	$963.47		$1,059.6167	$1,059.62	$1,059.60	$1,059.50