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	$57.60	7.536%	$61.9407	$61.94	$61.95	$61.90
Purchase #2	$33.68	7.382%	$36.1663	$36.17	$36.15	$36.20
Purchase #3	$12.37	7.350%	$13.2792	$13.28	$13.30	$13.30
Purchase #4	$50.45	11.601%	$56.3027	$56.30	$56.30	$56.30
Purchase #5	$38.55	12.478%	$43.3603	$43.36	$43.35	$43.40
Purchase #6	$43.50	13.183%	$49.2346	$49.23	$49.25	$49.20
Purchase #7	$51.26	4.589%	$53.6123	$53.61	$53.60	$53.60
7 purchase totals =	$287.41		$313.8961	$313.89	$313.90	$313.90