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	$188.39	4.773%	$197.3819	$197.38	$197.40	$197.40
Purchase #2	$179.88	3.154%	$185.5534	$185.55	$185.55	$185.60
Purchase #3	$212.40	4.863%	$222.729	$222.73	$222.75	$222.70
Purchase #4	$195.77	4.294%	$204.1764	$204.18	$204.20	$204.20
Purchase #5	$247.42	6.229%	$262.8318	$262.83	$262.85	$262.80
Purchase #6	$67.71	5.387%	$71.3575	$71.36	$71.35	$71.40
Purchase #7	$10.38	13.734%	$11.8056	$11.81	$11.80	$11.80
7 purchase totals =	$1,101.95		$1,155.8356	$1,155.84	$1,155.90	$1,155.90