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	$164.47	10.575%	$181.8627	$181.86	$181.85	$181.90
Purchase #2	$165.44	4.359%	$172.6515	$172.65	$172.65	$172.70
Purchase #3	$94.61	8.771%	$102.9082	$102.91	$102.90	$102.90
Purchase #4	$109.90	4.154%	$114.4652	$114.47	$114.45	$114.50
Purchase #5	$241.59	5.187%	$254.1213	$254.12	$254.10	$254.10
Purchase #6	$168.37	12.498%	$189.4129	$189.41	$189.40	$189.40
Purchase #7	$105.48	10.365%	$116.413	$116.41	$116.40	$116.40
7 purchase totals =	$1,049.86		$1,131.8348	$1,131.83	$1,131.75	$1,131.90