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	$130.85	11.508%	$145.9082	$145.91	$145.90	$145.90
Purchase #2	$156.55	4.822%	$164.0988	$164.10	$164.10	$164.10
Purchase #3	$153.57	12.590%	$172.9045	$172.90	$172.90	$172.90
Purchase #4	$194.31	3.473%	$201.0584	$201.06	$201.05	$201.10
Purchase #5	$5.77	10.142%	$6.3552	$6.36	$6.35	$6.40
Purchase #6	$95.76	9.749%	$105.0956	$105.10	$105.10	$105.10
Purchase #7	$181.43	13.273%	$205.5112	$205.51	$205.50	$205.50
7 purchase totals =	$918.24		$1,000.9319	$1,000.94	$1,000.90	$1,001.00