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	$214.39	6.257%	$227.8044	$227.80	$227.80	$227.80
Purchase #2	$87.34	4.474%	$91.2476	$91.25	$91.25	$91.20
Purchase #3	$35.89	5.127%	$37.7301	$37.73	$37.75	$37.70
Purchase #4	$135.37	6.871%	$144.6713	$144.67	$144.65	$144.70
Purchase #5	$211.46	9.655%	$231.8765	$231.88	$231.90	$231.90
Purchase #6	$209.75	11.442%	$233.7496	$233.75	$233.75	$233.70
Purchase #7	$131.44	7.669%	$141.5201	$141.52	$141.50	$141.50
7 purchase totals =	$1,025.64		$1,108.5996	$1,108.60	$1,108.60	$1,108.50