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	$177.84	8.804%	$193.497	$193.50	$193.50	$193.50
Purchase #2	$228.80	8.454%	$248.1428	$248.14	$248.15	$248.10
Purchase #3	$42.67	5.650%	$45.0809	$45.08	$45.10	$45.10
Purchase #4	$203.45	5.841%	$215.3335	$215.33	$215.35	$215.30
Purchase #5	$79.50	5.566%	$83.925	$83.93	$83.95	$83.90
Purchase #6	$68.86	5.794%	$72.8497	$72.85	$72.85	$72.80
Purchase #7	$184.59	6.433%	$196.4647	$196.46	$196.45	$196.50
7 purchase totals =	$985.71		$1,055.2936	$1,055.29	$1,055.35	$1,055.20