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	$118.29	4.381%	$123.4723	$123.47	$123.45	$123.50
Purchase #2	$136.30	3.696%	$141.3376	$141.34	$141.35	$141.30
Purchase #3	$195.29	9.627%	$214.0906	$214.09	$214.10	$214.10
Purchase #4	$61.53	9.558%	$67.411	$67.41	$67.40	$67.40
Purchase #5	$109.36	10.585%	$120.9358	$120.94	$120.95	$120.90
Purchase #6	$211.96	5.479%	$223.5733	$223.57	$223.55	$223.60
Purchase #7	$164.58	10.255%	$181.4577	$181.46	$181.45	$181.50
7 purchase totals =	$997.31		$1,072.2783	$1,072.28	$1,072.25	$1,072.30