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	$237.76	10.129%	$261.8427	$261.84	$261.85	$261.80
Purchase #2	$236.67	9.660%	$259.5323	$259.53	$259.55	$259.50
Purchase #3	$218.42	3.140%	$225.2784	$225.28	$225.30	$225.30
Purchase #4	$136.71	4.142%	$142.3725	$142.37	$142.35	$142.40
Purchase #5	$114.47	11.146%	$127.2288	$127.23	$127.25	$127.20
Purchase #6	$207.41	6.770%	$221.4517	$221.45	$221.45	$221.50
Purchase #7	$203.47	9.755%	$223.3185	$223.32	$223.30	$223.30
7 purchase totals =	$1,354.91		$1,461.0249	$1,461.02	$1,461.05	$1,461.00