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	$211.97	4.509%	$221.5277	$221.53	$221.55	$221.50
Purchase #2	$193.87	9.592%	$212.466	$212.47	$212.45	$212.50
Purchase #3	$182.49	7.714%	$196.5673	$196.57	$196.55	$196.60
Purchase #4	$155.41	4.437%	$162.3055	$162.31	$162.30	$162.30
Purchase #5	$157.76	8.640%	$171.3905	$171.39	$171.40	$171.40
Purchase #6	$188.75	6.437%	$200.8998	$200.90	$200.90	$200.90
Purchase #7	$15.39	5.841%	$16.2889	$16.29	$16.30	$16.30
7 purchase totals =	$1,105.64		$1,181.4457	$1,181.46	$1,181.45	$1,181.50