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	$49.57	5.422%	$52.2577	$52.26	$52.25	$52.30
Purchase #2	$163.71	10.795%	$181.3825	$181.38	$181.40	$181.40
Purchase #3	$26.72	9.738%	$29.322	$29.32	$29.30	$29.30
Purchase #4	$198.51	10.680%	$219.7109	$219.71	$219.70	$219.70
Purchase #5	$226.59	12.616%	$255.1766	$255.18	$255.20	$255.20
Purchase #6	$78.71	12.354%	$88.4338	$88.43	$88.45	$88.40
Purchase #7	$189.79	3.346%	$196.1404	$196.14	$196.15	$196.10
7 purchase totals =	$933.60		$1,022.4239	$1,022.42	$1,022.45	$1,022.40