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	$191.44	7.479%	$205.7578	$205.76	$205.75	$205.80
Purchase #2	$18.43	13.750%	$20.9641	$20.96	$20.95	$21.00
Purchase #3	$233.56	4.827%	$244.8339	$244.83	$244.85	$244.80
Purchase #4	$164.26	10.680%	$181.803	$181.80	$181.80	$181.80
Purchase #5	$136.78	8.764%	$148.7674	$148.77	$148.75	$148.80
Purchase #6	$60.91	5.472%	$64.243	$64.24	$64.25	$64.20
Purchase #7	$221.44	10.595%	$244.9016	$244.90	$244.90	$244.90
7 purchase totals =	$1,026.82		$1,111.2708	$1,111.26	$1,111.25	$1,111.30