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	$217.33	7.351%	$233.3059	$233.31	$233.30	$233.30
Purchase #2	$48.39	13.201%	$54.778	$54.78	$54.80	$54.80
Purchase #3	$148.56	5.319%	$156.4619	$156.46	$156.45	$156.50
Purchase #4	$84.59	7.590%	$91.0104	$91.01	$91.00	$91.00
Purchase #5	$152.50	11.314%	$169.7539	$169.75	$169.75	$169.80
Purchase #6	$116.48	7.178%	$124.8409	$124.84	$124.85	$124.80
Purchase #7	$179.26	3.817%	$186.1024	$186.10	$186.10	$186.10
7 purchase totals =	$947.11		$1,016.2534	$1,016.25	$1,016.25	$1,016.30