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	$208.32	3.414%	$215.432	$215.43	$215.45	$215.40
Purchase #2	$184.86	3.474%	$191.282	$191.28	$191.30	$191.30
Purchase #3	$49.32	12.867%	$55.666	$55.67	$55.65	$55.70
Purchase #4	$130.67	11.141%	$145.2279	$145.23	$145.25	$145.20
Purchase #5	$29.56	13.174%	$33.4542	$33.45	$33.45	$33.50
Purchase #6	$185.40	6.867%	$198.1314	$198.13	$198.15	$198.10
Purchase #7	$150.87	8.821%	$164.1782	$164.18	$164.20	$164.20
7 purchase totals =	$939.00		$1,003.3717	$1,003.37	$1,003.45	$1,003.40