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	$209.26	13.267%	$237.0225	$237.02	$237.00	$237.00
Purchase #2	$11.82	7.836%	$12.7462	$12.75	$12.75	$12.70
Purchase #3	$242.29	11.701%	$270.6404	$270.64	$270.65	$270.60
Purchase #4	$135.71	6.379%	$144.3669	$144.37	$144.35	$144.40
Purchase #5	$209.75	13.622%	$238.3221	$238.32	$238.30	$238.30
Purchase #6	$50.69	13.600%	$57.5838	$57.58	$57.60	$57.60
Purchase #7	$89.47	11.611%	$99.8584	$99.86	$99.85	$99.90
7 purchase totals =	$948.99		$1,060.5403	$1,060.54	$1,060.50	$1,060.50