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	$91.89	10.625%	$101.6533	$101.65	$101.65	$101.70
Purchase #2	$91.80	11.362%	$102.2303	$102.23	$102.25	$102.20
Purchase #3	$27.87	3.481%	$28.8402	$28.84	$28.85	$28.80
Purchase #4	$37.53	8.568%	$40.7456	$40.75	$40.75	$40.70
Purchase #5	$60.71	6.598%	$64.7156	$64.72	$64.70	$64.70
Purchase #6	$240.97	6.162%	$255.8186	$255.82	$255.80	$255.80
Purchase #7	$150.41	6.111%	$159.6016	$159.60	$159.60	$159.60
7 purchase totals =	$701.18		$753.6052	$753.61	$753.60	$753.50