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	$219.26	7.863%	$236.5004	$236.50	$236.50	$236.50
Purchase #2	$55.97	10.517%	$61.8564	$61.86	$61.85	$61.90
Purchase #3	$30.39	10.139%	$33.4712	$33.47	$33.45	$33.50
Purchase #4	$219.94	13.332%	$249.2624	$249.26	$249.25	$249.30
Purchase #5	$124.65	7.146%	$133.5575	$133.56	$133.55	$133.60
Purchase #6	$208.82	7.113%	$223.6734	$223.67	$223.65	$223.70
Purchase #7	$119.69	3.237%	$123.5644	$123.56	$123.55	$123.60
7 purchase totals =	$978.72		$1,061.8857	$1,061.88	$1,061.80	$1,062.10