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	$153.78	11.389%	$171.294	$171.29	$171.30	$171.30
Purchase #2	$241.31	5.818%	$255.3494	$255.35	$255.35	$255.30
Purchase #3	$36.90	6.863%	$39.4324	$39.43	$39.45	$39.40
Purchase #4	$109.34	6.746%	$116.7161	$116.72	$116.70	$116.70
Purchase #5	$126.71	11.594%	$141.4008	$141.40	$141.40	$141.40
Purchase #6	$235.72	12.331%	$264.7866	$264.79	$264.80	$264.80
Purchase #7	$197.82	3.441%	$204.627	$204.63	$204.65	$204.60
7 purchase totals =	$1,101.58		$1,193.6063	$1,193.61	$1,193.65	$1,193.50