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	$175.81	10.603%	$194.4511	$194.45	$194.45	$194.50
Purchase #2	$14.63	10.178%	$16.119	$16.12	$16.10	$16.10
Purchase #3	$64.32	5.267%	$67.7077	$67.71	$67.70	$67.70
Purchase #4	$182.74	7.411%	$196.2829	$196.28	$196.30	$196.30
Purchase #5	$215.98	12.578%	$243.146	$243.15	$243.15	$243.10
Purchase #6	$30.38	10.366%	$33.5292	$33.53	$33.55	$33.50
Purchase #7	$12.96	12.509%	$14.5812	$14.58	$14.60	$14.60
7 purchase totals =	$696.82		$765.8171	$765.82	$765.85	$765.80