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	$112.53	11.501%	$125.4721	$125.47	$125.45	$125.50
Purchase #2	$157.89	4.121%	$164.3966	$164.40	$164.40	$164.40
Purchase #3	$203.80	9.116%	$222.3784	$222.38	$222.40	$222.40
Purchase #4	$215.39	5.719%	$227.7082	$227.71	$227.70	$227.70
Purchase #5	$57.33	7.611%	$61.6934	$61.69	$61.70	$61.70
Purchase #6	$102.71	11.299%	$114.3152	$114.32	$114.30	$114.30
Purchase #7	$90.81	11.676%	$101.413	$101.41	$101.40	$101.40
7 purchase totals =	$940.46		$1,017.3769	$1,017.38	$1,017.35	$1,017.40