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	$56.31	12.314%	$63.244	$63.24	$63.25	$63.20
Purchase #2	$130.80	10.393%	$144.394	$144.39	$144.40	$144.40
Purchase #3	$41.68	3.445%	$43.1159	$43.12	$43.10	$43.10
Purchase #4	$158.36	11.444%	$176.4827	$176.48	$176.50	$176.50
Purchase #5	$176.60	7.520%	$189.8803	$189.88	$189.90	$189.90
Purchase #6	$198.76	12.428%	$223.4619	$223.46	$223.45	$223.50
Purchase #7	$198.56	8.543%	$215.523	$215.52	$215.50	$215.50
7 purchase totals =	$961.07		$1,056.1018	$1,056.09	$1,056.10	$1,056.10