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	$100.28	3.737%	$104.0275	$104.03	$104.05	$104.00
Purchase #2	$236.34	3.732%	$245.1602	$245.16	$245.15	$245.20
Purchase #3	$82.86	5.368%	$87.3079	$87.31	$87.30	$87.30
Purchase #4	$61.30	11.803%	$68.5352	$68.54	$68.55	$68.50
Purchase #5	$117.78	10.617%	$130.2847	$130.28	$130.30	$130.30
Purchase #6	$206.80	7.385%	$222.0722	$222.07	$222.05	$222.10
Purchase #7	$242.79	4.455%	$253.6063	$253.61	$253.60	$253.60
7 purchase totals =	$1,048.15		$1,110.9940	$1,111.00	$1,111.00	$1,111.00