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	$245.29	6.615%	$261.5159	$261.52	$261.50	$261.50
Purchase #2	$57.25	4.585%	$59.8749	$59.87	$59.85	$59.90
Purchase #3	$169.97	4.160%	$177.0408	$177.04	$177.05	$177.00
Purchase #4	$215.81	6.552%	$229.9499	$229.95	$229.95	$229.90
Purchase #5	$183.48	4.607%	$191.9329	$191.93	$191.95	$191.90
Purchase #6	$68.67	13.675%	$78.0606	$78.06	$78.05	$78.10
Purchase #7	$81.88	5.216%	$86.1509	$86.15	$86.15	$86.20
7 purchase totals =	$1,022.35		$1,084.5259	$1,084.52	$1,084.50	$1,084.50