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	$191.29	9.630%	$209.7112	$209.71	$209.70	$209.70
Purchase #2	$171.47	8.203%	$185.5357	$185.54	$185.55	$185.50
Purchase #3	$44.45	5.723%	$46.9939	$46.99	$47.00	$47.00
Purchase #4	$175.43	8.752%	$190.7836	$190.78	$190.80	$190.80
Purchase #5	$157.96	9.249%	$172.5697	$172.57	$172.55	$172.60
Purchase #6	$181.77	6.488%	$193.5632	$193.56	$193.55	$193.60
Purchase #7	$63.32	6.172%	$67.2281	$67.23	$67.25	$67.20
7 purchase totals =	$985.69		$1,066.3854	$1,066.38	$1,066.40	$1,066.40