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	$197.90	9.122%	$215.9524	$215.95	$215.95	$216.00
Purchase #2	$183.70	6.873%	$196.3257	$196.33	$196.35	$196.30
Purchase #3	$135.31	5.635%	$142.9347	$142.93	$142.95	$142.90
Purchase #4	$44.26	3.554%	$45.833	$45.83	$45.85	$45.80
Purchase #5	$250.95	12.498%	$282.3137	$282.31	$282.30	$282.30
Purchase #6	$173.91	4.170%	$181.162	$181.16	$181.15	$181.20
Purchase #7	$167.36	11.247%	$186.183	$186.18	$186.20	$186.20
7 purchase totals =	$1,153.39		$1,250.7045	$1,250.69	$1,250.75	$1,250.70