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	$116.38	8.580%	$126.3654	$126.37	$126.35	$126.40
Purchase #2	$111.32	11.110%	$123.6877	$123.69	$123.70	$123.70
Purchase #3	$8.58	11.414%	$9.5593	$9.56	$9.55	$9.60
Purchase #4	$53.92	10.470%	$59.5654	$59.57	$59.55	$59.60
Purchase #5	$59.69	13.433%	$67.7082	$67.71	$67.70	$67.70
Purchase #6	$54.66	13.851%	$62.231	$62.23	$62.25	$62.20
Purchase #7	$225.33	11.753%	$251.813	$251.81	$251.80	$251.80
7 purchase totals =	$629.88		$700.9300	$700.94	$700.90	$701.00