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	$195.63	4.322%	$204.0851	$204.09	$204.10	$204.10
Purchase #2	$164.28	4.425%	$171.5494	$171.55	$171.55	$171.50
Purchase #3	$140.88	3.354%	$145.6051	$145.61	$145.60	$145.60
Purchase #4	$146.98	6.190%	$156.0781	$156.08	$156.10	$156.10
Purchase #5	$130.51	10.729%	$144.5124	$144.51	$144.50	$144.50
Purchase #6	$189.30	3.806%	$196.5048	$196.50	$196.50	$196.50
Purchase #7	$191.91	13.222%	$217.2843	$217.28	$217.30	$217.30
7 purchase totals =	$1,159.49		$1,235.6192	$1,235.62	$1,235.65	$1,235.60