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	$213.62	10.380%	$235.7938	$235.79	$235.80	$235.80
Purchase #2	$39.47	3.749%	$40.9497	$40.95	$40.95	$40.90
Purchase #3	$40.54	7.371%	$43.5282	$43.53	$43.55	$43.50
Purchase #4	$229.84	4.173%	$239.4312	$239.43	$239.45	$239.40
Purchase #5	$131.89	5.615%	$139.2956	$139.30	$139.30	$139.30
Purchase #6	$101.80	3.392%	$105.2531	$105.25	$105.25	$105.30
Purchase #7	$195.63	4.828%	$205.075	$205.08	$205.10	$205.10
7 purchase totals =	$952.79		$1,009.3266	$1,009.33	$1,009.40	$1,009.30