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	$92.32	10.296%	$101.8253	$101.83	$101.85	$101.80
Purchase #2	$112.71	4.303%	$117.5599	$117.56	$117.55	$117.60
Purchase #3	$107.46	9.600%	$117.7762	$117.78	$117.80	$117.80
Purchase #4	$209.36	6.592%	$223.161	$223.16	$223.15	$223.20
Purchase #5	$217.86	5.342%	$229.4981	$229.50	$229.50	$229.50
Purchase #6	$127.87	9.798%	$140.3987	$140.40	$140.40	$140.40
Purchase #7	$82.76	5.168%	$87.037	$87.04	$87.05	$87.00
7 purchase totals =	$950.34		$1,017.2562	$1,017.27	$1,017.30	$1,017.30