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	$88.85	5.592%	$93.8185	$93.82	$93.80	$93.80
Purchase #2	$241.85	7.558%	$260.129	$260.13	$260.15	$260.10
Purchase #3	$185.61	5.646%	$196.0895	$196.09	$196.10	$196.10
Purchase #4	$65.96	7.738%	$71.064	$71.06	$71.05	$71.10
Purchase #5	$183.99	13.254%	$208.376	$208.38	$208.40	$208.40
Purchase #6	$89.75	11.514%	$100.0838	$100.08	$100.10	$100.10
Purchase #7	$171.31	4.488%	$178.9984	$179.00	$179.00	$179.00
7 purchase totals =	$1,027.32		$1,108.5592	$1,108.56	$1,108.60	$1,108.60