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	$52.63	12.362%	$59.1361	$59.14	$59.15	$59.10
Purchase #2	$176.46	3.317%	$182.3132	$182.31	$182.30	$182.30
Purchase #3	$151.71	3.523%	$157.0547	$157.05	$157.05	$157.10
Purchase #4	$19.43	7.455%	$20.8785	$20.88	$20.90	$20.90
Purchase #5	$168.27	13.590%	$191.1379	$191.14	$191.15	$191.10
Purchase #6	$209.85	10.518%	$231.922	$231.92	$231.90	$231.90
Purchase #7	$242.75	4.431%	$253.5063	$253.51	$253.50	$253.50
7 purchase totals =	$1,021.10		$1,095.9487	$1,095.95	$1,095.95	$1,095.90