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	$190.99	10.276%	$210.6161	$210.62	$210.60	$210.60
Purchase #2	$63.69	3.107%	$65.6688	$65.67	$65.65	$65.70
Purchase #3	$82.58	10.721%	$91.4334	$91.43	$91.45	$91.40
Purchase #4	$176.33	7.289%	$189.1827	$189.18	$189.20	$189.20
Purchase #5	$40.29	10.504%	$44.5221	$44.52	$44.50	$44.50
Purchase #6	$205.46	5.549%	$216.861	$216.86	$216.85	$216.90
Purchase #7	$182.66	4.206%	$190.3427	$190.34	$190.35	$190.30
7 purchase totals =	$942.00		$1,008.6268	$1,008.62	$1,008.60	$1,008.60