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	$117.61	10.816%	$130.3307	$130.33	$130.35	$130.30
Purchase #2	$196.94	10.306%	$217.2366	$217.24	$217.25	$217.20
Purchase #3	$114.70	10.761%	$127.0429	$127.04	$127.05	$127.00
Purchase #4	$168.29	12.256%	$188.9156	$188.92	$188.90	$188.90
Purchase #5	$192.42	12.718%	$216.892	$216.89	$216.90	$216.90
Purchase #6	$20.98	7.397%	$22.5319	$22.53	$22.55	$22.50
Purchase #7	$207.53	11.613%	$231.6305	$231.63	$231.65	$231.60
7 purchase totals =	$1,018.47		$1,134.5802	$1,134.58	$1,134.65	$1,134.40