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	$196.43	10.416%	$216.8901	$216.89	$216.90	$216.90
Purchase #2	$128.69	11.589%	$143.6039	$143.60	$143.60	$143.60
Purchase #3	$37.59	13.314%	$42.5947	$42.59	$42.60	$42.60
Purchase #4	$236.37	10.320%	$260.7634	$260.76	$260.75	$260.80
Purchase #5	$246.75	9.733%	$270.7662	$270.77	$270.75	$270.80
Purchase #6	$59.77	12.794%	$67.417	$67.42	$67.40	$67.40
Purchase #7	$88.66	5.400%	$93.4476	$93.45	$93.45	$93.40
7 purchase totals =	$994.26		$1,095.4829	$1,095.48	$1,095.45	$1,095.50