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	$57.44	13.502%	$65.1955	$65.20	$65.20	$65.20
Purchase #2	$112.67	6.705%	$120.2245	$120.22	$120.20	$120.20
Purchase #3	$157.96	4.341%	$164.817	$164.82	$164.80	$164.80
Purchase #4	$241.26	13.822%	$274.607	$274.61	$274.60	$274.60
Purchase #5	$69.76	3.548%	$72.2351	$72.24	$72.25	$72.20
Purchase #6	$143.65	8.850%	$156.363	$156.36	$156.35	$156.40
Purchase #7	$238.43	7.542%	$256.4124	$256.41	$256.40	$256.40
7 purchase totals =	$1,021.17		$1,109.8545	$1,109.86	$1,109.80	$1,109.80