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	$59.67	4.453%	$62.3271	$62.33	$62.35	$62.30
Purchase #2	$100.37	4.688%	$105.0753	$105.08	$105.10	$105.10
Purchase #3	$163.98	10.822%	$181.7259	$181.73	$181.75	$181.70
Purchase #4	$184.25	7.468%	$198.0098	$198.01	$198.00	$198.00
Purchase #5	$228.45	4.460%	$238.6389	$238.64	$238.65	$238.60
Purchase #6	$162.74	4.207%	$169.5865	$169.59	$169.60	$169.60
Purchase #7	$87.28	13.517%	$99.0776	$99.08	$99.10	$99.10
7 purchase totals =	$986.74		$1,054.4411	$1,054.46	$1,054.55	$1,054.40