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	$68.70	3.404%	$71.0385	$71.04	$71.05	$71.00
Purchase #2	$206.62	5.300%	$217.5709	$217.57	$217.55	$217.60
Purchase #3	$212.46	3.791%	$220.5144	$220.51	$220.50	$220.50
Purchase #4	$115.59	10.109%	$127.275	$127.28	$127.30	$127.30
Purchase #5	$19.49	12.148%	$21.8576	$21.86	$21.85	$21.90
Purchase #6	$30.71	7.645%	$33.0578	$33.06	$33.05	$33.10
Purchase #7	$233.40	8.613%	$253.5027	$253.50	$253.50	$253.50
7 purchase totals =	$886.97		$944.8169	$944.82	$944.80	$944.90