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	$114.36	8.725%	$124.3379	$124.34	$124.35	$124.30
Purchase #2	$172.45	11.147%	$191.673	$191.67	$191.65	$191.70
Purchase #3	$83.55	6.290%	$88.8053	$88.81	$88.80	$88.80
Purchase #4	$139.99	4.122%	$145.7604	$145.76	$145.75	$145.80
Purchase #5	$145.31	4.125%	$151.304	$151.30	$151.30	$151.30
Purchase #6	$84.83	6.732%	$90.5408	$90.54	$90.55	$90.50
Purchase #7	$224.82	4.187%	$234.2332	$234.23	$234.25	$234.20
7 purchase totals =	$965.31		$1,026.6546	$1,026.65	$1,026.65	$1,026.60