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	$59.76	5.318%	$62.938	$62.94	$62.95	$62.90
Purchase #2	$196.90	5.469%	$207.6685	$207.67	$207.65	$207.70
Purchase #3	$208.30	12.206%	$233.7251	$233.73	$233.75	$233.70
Purchase #4	$169.80	12.201%	$190.5173	$190.52	$190.50	$190.50
Purchase #5	$122.73	3.828%	$127.4281	$127.43	$127.45	$127.40
Purchase #6	$175.47	7.236%	$188.167	$188.17	$188.15	$188.20
Purchase #7	$198.35	12.314%	$222.7748	$222.77	$222.75	$222.80
7 purchase totals =	$1,131.31		$1,233.2188	$1,233.23	$1,233.20	$1,233.20