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	$201.54	3.484%	$208.5617	$208.56	$208.55	$208.60
Purchase #2	$214.35	3.628%	$222.1266	$222.13	$222.15	$222.10
Purchase #3	$178.74	9.800%	$196.2565	$196.26	$196.25	$196.30
Purchase #4	$26.74	6.500%	$28.4781	$28.48	$28.50	$28.50
Purchase #5	$57.35	11.756%	$64.0921	$64.09	$64.10	$64.10
Purchase #6	$189.84	8.156%	$205.3234	$205.32	$205.30	$205.30
Purchase #7	$109.31	13.714%	$124.3008	$124.30	$124.30	$124.30
7 purchase totals =	$977.87		$1,049.1392	$1,049.14	$1,049.15	$1,049.20