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	$230.68	3.379%	$238.4747	$238.47	$238.45	$238.50
Purchase #2	$177.51	7.780%	$191.3203	$191.32	$191.30	$191.30
Purchase #3	$61.96	7.632%	$66.6888	$66.69	$66.70	$66.70
Purchase #4	$168.91	7.498%	$181.5749	$181.57	$181.55	$181.60
Purchase #5	$69.39	11.515%	$77.3803	$77.38	$77.40	$77.40
Purchase #6	$123.33	6.387%	$131.2071	$131.21	$131.20	$131.20
Purchase #7	$150.83	11.160%	$167.6626	$167.66	$167.65	$167.70
7 purchase totals =	$982.61		$1,054.3087	$1,054.30	$1,054.25	$1,054.40