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	$179.46	6.527%	$191.1734	$191.17	$191.15	$191.20
Purchase #2	$236.77	7.779%	$255.1883	$255.19	$255.20	$255.20
Purchase #3	$129.56	9.709%	$142.139	$142.14	$142.15	$142.10
Purchase #4	$92.88	10.706%	$102.8237	$102.82	$102.80	$102.80
Purchase #5	$182.68	3.335%	$188.7724	$188.77	$188.75	$188.80
Purchase #6	$149.46	11.575%	$166.76	$166.76	$166.75	$166.80
Purchase #7	$203.98	5.521%	$215.2417	$215.24	$215.25	$215.20
7 purchase totals =	$1,174.79		$1,262.0985	$1,262.09	$1,262.05	$1,262.10