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	$109.33	3.608%	$113.2746	$113.27	$113.25	$113.30
Purchase #2	$189.29	11.601%	$211.2495	$211.25	$211.25	$211.20
Purchase #3	$205.90	8.236%	$222.8579	$222.86	$222.85	$222.90
Purchase #4	$152.95	12.803%	$172.5322	$172.53	$172.55	$172.50
Purchase #5	$24.74	10.682%	$27.3827	$27.38	$27.40	$27.40
Purchase #6	$9.94	13.758%	$11.3075	$11.31	$11.30	$11.30
Purchase #7	$141.82	6.564%	$151.1291	$151.13	$151.15	$151.10
7 purchase totals =	$833.97		$909.7335	$909.73	$909.75	$909.70