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	$103.59	6.184%	$109.996	$110.00	$110.00	$110.00
Purchase #2	$197.42	10.669%	$218.4827	$218.48	$218.50	$218.50
Purchase #3	$86.47	12.705%	$97.456	$97.46	$97.45	$97.50
Purchase #4	$187.27	6.422%	$199.2965	$199.30	$199.30	$199.30
Purchase #5	$87.33	5.308%	$91.9655	$91.97	$91.95	$92.00
Purchase #6	$179.29	6.768%	$191.4243	$191.42	$191.40	$191.40
Purchase #7	$105.38	4.874%	$110.5162	$110.52	$110.50	$110.50
7 purchase totals =	$946.75		$1,019.1372	$1,019.15	$1,019.10	$1,019.20