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	$209.57	7.380%	$225.0363	$225.04	$225.05	$225.00
Purchase #2	$85.39	5.258%	$89.8798	$89.88	$89.90	$89.90
Purchase #3	$158.71	11.117%	$176.3538	$176.35	$176.35	$176.40
Purchase #4	$103.39	11.267%	$115.039	$115.04	$115.05	$115.00
Purchase #5	$81.39	8.681%	$88.4555	$88.46	$88.45	$88.50
Purchase #6	$101.61	10.810%	$112.594	$112.59	$112.60	$112.60
Purchase #7	$210.42	4.342%	$219.5564	$219.56	$219.55	$219.60
7 purchase totals =	$950.48		$1,026.9148	$1,026.92	$1,026.95	$1,027.00