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	$76.49	13.661%	$86.9393	$86.94	$86.95	$86.90
Purchase #2	$181.67	3.541%	$188.1029	$188.10	$188.10	$188.10
Purchase #3	$178.27	10.372%	$196.7602	$196.76	$196.75	$196.80
Purchase #4	$201.41	11.123%	$223.8128	$223.81	$223.80	$223.80
Purchase #5	$116.70	3.128%	$120.3504	$120.35	$120.35	$120.40
Purchase #6	$101.46	13.592%	$115.2504	$115.25	$115.25	$115.30
Purchase #7	$141.96	6.493%	$151.1775	$151.18	$151.20	$151.20
7 purchase totals =	$997.96		$1,082.3935	$1,082.39	$1,082.40	$1,082.50