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	$172.38	10.605%	$190.6609	$190.66	$190.65	$190.70
Purchase #2	$105.90	4.235%	$110.3849	$110.38	$110.40	$110.40
Purchase #3	$184.60	8.538%	$200.3611	$200.36	$200.35	$200.40
Purchase #4	$192.86	11.864%	$215.7409	$215.74	$215.75	$215.70
Purchase #5	$52.41	3.768%	$54.3848	$54.38	$54.40	$54.40
Purchase #6	$137.67	3.281%	$142.187	$142.19	$142.20	$142.20
Purchase #7	$190.83	3.506%	$197.5205	$197.52	$197.50	$197.50
7 purchase totals =	$1,036.65		$1,111.2401	$1,111.23	$1,111.25	$1,111.30