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	$163.92	4.785%	$171.7636	$171.76	$171.75	$171.80
Purchase #2	$240.28	4.732%	$251.65	$251.65	$251.65	$251.70
Purchase #3	$180.90	8.501%	$196.2783	$196.28	$196.30	$196.30
Purchase #4	$178.56	3.868%	$185.4667	$185.47	$185.45	$185.50
Purchase #5	$160.67	8.466%	$174.2723	$174.27	$174.25	$174.30
Purchase #6	$127.27	10.822%	$141.0432	$141.04	$141.05	$141.00
Purchase #7	$84.37	5.642%	$89.1302	$89.13	$89.15	$89.10
7 purchase totals =	$1,135.97		$1,209.6043	$1,209.60	$1,209.60	$1,209.70