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	$58.49	6.622%	$62.3632	$62.36	$62.35	$62.40
Purchase #2	$116.28	7.288%	$124.7545	$124.75	$124.75	$124.80
Purchase #3	$85.53	6.445%	$91.0424	$91.04	$91.05	$91.00
Purchase #4	$198.32	11.486%	$221.099	$221.10	$221.10	$221.10
Purchase #5	$117.33	8.672%	$127.5049	$127.50	$127.50	$127.50
Purchase #6	$109.55	13.639%	$124.4915	$124.49	$124.50	$124.50
Purchase #7	$14.47	3.113%	$14.9205	$14.92	$14.90	$14.90
7 purchase totals =	$699.97		$766.1760	$766.16	$766.15	$766.20