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	$164.80	4.193%	$171.7101	$171.71	$171.70	$171.70
Purchase #2	$89.33	5.565%	$94.3012	$94.30	$94.30	$94.30
Purchase #3	$247.48	6.712%	$264.0909	$264.09	$264.10	$264.10
Purchase #4	$207.48	13.497%	$235.4836	$235.48	$235.50	$235.50
Purchase #5	$89.47	12.323%	$100.4954	$100.50	$100.50	$100.50
Purchase #6	$57.77	5.613%	$61.0126	$61.01	$61.00	$61.00
Purchase #7	$105.97	7.849%	$114.2876	$114.29	$114.30	$114.30
7 purchase totals =	$962.30		$1,041.3814	$1,041.38	$1,041.40	$1,041.40