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	$184.95	5.717%	$195.5236	$195.52	$195.50	$195.50
Purchase #2	$170.64	5.420%	$179.8887	$179.89	$179.90	$179.90
Purchase #3	$154.46	7.733%	$166.4044	$166.40	$166.40	$166.40
Purchase #4	$151.33	13.495%	$171.752	$171.75	$171.75	$171.80
Purchase #5	$132.87	8.757%	$144.5054	$144.51	$144.50	$144.50
Purchase #6	$114.73	4.190%	$119.5372	$119.54	$119.55	$119.50
Purchase #7	$36.68	4.542%	$38.346	$38.35	$38.35	$38.30
7 purchase totals =	$945.66		$1,015.9573	$1,015.96	$1,015.95	$1,015.90