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	$184.32	8.849%	$200.6305	$200.63	$200.65	$200.60
Purchase #2	$185.55	4.835%	$194.5213	$194.52	$194.50	$194.50
Purchase #3	$102.52	3.250%	$105.8519	$105.85	$105.85	$105.90
Purchase #4	$250.69	11.736%	$280.111	$280.11	$280.10	$280.10
Purchase #5	$68.87	3.598%	$71.3479	$71.35	$71.35	$71.30
Purchase #6	$83.94	9.627%	$92.0209	$92.02	$92.00	$92.00
Purchase #7	$113.75	4.461%	$118.8244	$118.82	$118.80	$118.80
7 purchase totals =	$989.64		$1,063.3079	$1,063.30	$1,063.25	$1,063.20