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	$136.95	8.674%	$148.829	$148.83	$148.85	$148.80
Purchase #2	$37.28	3.330%	$38.5214	$38.52	$38.50	$38.50
Purchase #3	$211.36	9.346%	$231.1137	$231.11	$231.10	$231.10
Purchase #4	$189.32	5.754%	$200.2135	$200.21	$200.20	$200.20
Purchase #5	$176.75	7.316%	$189.681	$189.68	$189.70	$189.70
Purchase #6	$136.47	5.748%	$144.3143	$144.31	$144.30	$144.30
Purchase #7	$61.85	3.268%	$63.8713	$63.87	$63.85	$63.90
7 purchase totals =	$949.98		$1,016.5442	$1,016.53	$1,016.50	$1,016.50