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	$195.57	4.823%	$205.0023	$205.00	$205.00	$205.00
Purchase #2	$49.40	7.501%	$53.1055	$53.11	$53.10	$53.10
Purchase #3	$130.51	13.709%	$148.4016	$148.40	$148.40	$148.40
Purchase #4	$134.65	6.527%	$143.4386	$143.44	$143.45	$143.40
Purchase #5	$190.38	3.197%	$196.4664	$196.47	$196.45	$196.50
Purchase #6	$24.71	9.304%	$27.009	$27.01	$27.00	$27.00
Purchase #7	$219.63	11.347%	$244.5514	$244.55	$244.55	$244.60
7 purchase totals =	$944.85		$1,017.9748	$1,017.98	$1,017.95	$1,018.00