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	$212.53	6.211%	$225.7302	$225.73	$225.75	$225.70
Purchase #2	$79.94	6.309%	$84.9834	$84.98	$85.00	$85.00
Purchase #3	$65.86	9.802%	$72.3156	$72.32	$72.30	$72.30
Purchase #4	$91.55	10.647%	$101.2973	$101.30	$101.30	$101.30
Purchase #5	$116.46	13.262%	$131.9049	$131.90	$131.90	$131.90
Purchase #6	$161.40	12.568%	$181.6848	$181.68	$181.70	$181.70
Purchase #7	$96.83	13.208%	$109.6193	$109.62	$109.60	$109.60
7 purchase totals =	$824.57		$907.5355	$907.53	$907.55	$907.50