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	$82.78	4.447%	$86.4612	$86.46	$86.45	$86.50
Purchase #2	$99.46	11.544%	$110.9417	$110.94	$110.95	$110.90
Purchase #3	$238.67	5.695%	$252.2623	$252.26	$252.25	$252.30
Purchase #4	$201.77	3.853%	$209.5442	$209.54	$209.55	$209.50
Purchase #5	$123.97	6.161%	$131.6078	$131.61	$131.60	$131.60
Purchase #6	$193.67	11.224%	$215.4075	$215.41	$215.40	$215.40
Purchase #7	$82.51	7.363%	$88.5852	$88.59	$88.60	$88.60
7 purchase totals =	$1,022.83		$1,094.8099	$1,094.81	$1,094.80	$1,094.80