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	$194.84	7.186%	$208.8412	$208.84	$208.85	$208.80
Purchase #2	$162.65	3.102%	$167.6954	$167.70	$167.70	$167.70
Purchase #3	$125.96	4.535%	$131.6723	$131.67	$131.65	$131.70
Purchase #4	$126.90	13.300%	$143.7777	$143.78	$143.80	$143.80
Purchase #5	$62.93	11.398%	$70.1028	$70.10	$70.10	$70.10
Purchase #6	$109.90	3.427%	$113.6663	$113.67	$113.65	$113.70
Purchase #7	$229.32	13.107%	$259.377	$259.38	$259.40	$259.40
7 purchase totals =	$1,012.50		$1,095.1327	$1,095.14	$1,095.15	$1,095.20