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	$81.80	7.575%	$87.9964	$88.00	$88.00	$88.00
Purchase #2	$9.65	6.218%	$10.25	$10.25	$10.25	$10.30
Purchase #3	$167.38	10.841%	$185.5257	$185.53	$185.55	$185.50
Purchase #4	$222.59	4.482%	$232.5665	$232.57	$232.55	$232.60
Purchase #5	$235.44	4.354%	$245.6911	$245.69	$245.70	$245.70
Purchase #6	$118.96	7.551%	$127.9427	$127.94	$127.95	$127.90
Purchase #7	$247.65	10.848%	$274.5151	$274.52	$274.50	$274.50
7 purchase totals =	$1,083.47		$1,164.4875	$1,164.50	$1,164.50	$1,164.50