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	$196.35	6.816%	$209.7332	$209.73	$209.75	$209.70
Purchase #2	$151.34	11.374%	$168.5534	$168.55	$168.55	$168.60
Purchase #3	$92.82	11.434%	$103.433	$103.43	$103.45	$103.40
Purchase #4	$233.28	9.669%	$255.8358	$255.84	$255.85	$255.80
Purchase #5	$44.98	4.586%	$47.0428	$47.04	$47.05	$47.00
Purchase #6	$108.72	8.570%	$118.0373	$118.04	$118.05	$118.00
Purchase #7	$220.47	4.564%	$230.5323	$230.53	$230.55	$230.50
7 purchase totals =	$1,047.96		$1,133.1678	$1,133.16	$1,133.25	$1,133.00