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	$131.99	7.650%	$142.0872	$142.09	$142.10	$142.10
Purchase #2	$227.27	10.156%	$250.3515	$250.35	$250.35	$250.40
Purchase #3	$27.62	5.572%	$29.159	$29.16	$29.15	$29.20
Purchase #4	$107.95	5.764%	$114.1722	$114.17	$114.15	$114.20
Purchase #5	$78.40	6.666%	$83.6261	$83.63	$83.65	$83.60
Purchase #6	$242.78	7.665%	$261.3891	$261.39	$261.40	$261.40
Purchase #7	$198.40	12.636%	$223.4698	$223.47	$223.45	$223.50
7 purchase totals =	$1,014.41		$1,104.2549	$1,104.26	$1,104.25	$1,104.40