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	$119.31	5.116%	$125.4139	$125.41	$125.40	$125.40
Purchase #2	$53.83	10.160%	$59.2991	$59.30	$59.30	$59.30
Purchase #3	$62.55	7.662%	$67.3426	$67.34	$67.35	$67.30
Purchase #4	$118.61	9.513%	$129.8934	$129.89	$129.90	$129.90
Purchase #5	$133.89	13.669%	$152.1914	$152.19	$152.20	$152.20
Purchase #6	$247.41	3.170%	$255.2529	$255.25	$255.25	$255.30
Purchase #7	$51.51	7.529%	$55.3882	$55.39	$55.40	$55.40
7 purchase totals =	$787.11		$844.7815	$844.77	$844.80	$844.80