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	$88.39	6.476%	$94.1141	$94.11	$94.10	$94.10
Purchase #2	$154.39	8.574%	$167.6274	$167.63	$167.65	$167.60
Purchase #3	$67.39	8.645%	$73.2159	$73.22	$73.20	$73.20
Purchase #4	$191.61	5.238%	$201.6465	$201.65	$201.65	$201.60
Purchase #5	$133.41	8.713%	$145.034	$145.03	$145.05	$145.00
Purchase #6	$83.95	7.831%	$90.5241	$90.52	$90.50	$90.50
Purchase #7	$233.45	5.174%	$245.5287	$245.53	$245.55	$245.50
7 purchase totals =	$952.59		$1,017.6907	$1,017.69	$1,017.70	$1,017.50