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	$127.79	7.723%	$137.6592	$137.66	$137.65	$137.70
Purchase #2	$161.84	6.672%	$172.638	$172.64	$172.65	$172.60
Purchase #3	$189.46	11.774%	$211.767	$211.77	$211.75	$211.80
Purchase #4	$129.75	9.137%	$141.6053	$141.61	$141.60	$141.60
Purchase #5	$81.69	4.858%	$85.6585	$85.66	$85.65	$85.70
Purchase #6	$74.76	4.198%	$77.8984	$77.90	$77.90	$77.90
Purchase #7	$187.43	5.597%	$197.9205	$197.92	$197.90	$197.90
7 purchase totals =	$952.72		$1,025.1469	$1,025.16	$1,025.10	$1,025.20