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	$187.25	11.323%	$208.4523	$208.45	$208.45	$208.50
Purchase #2	$76.69	7.280%	$82.273	$82.27	$82.25	$82.30
Purchase #3	$200.89	4.307%	$209.5423	$209.54	$209.55	$209.50
Purchase #4	$216.63	3.570%	$224.3637	$224.36	$224.35	$224.40
Purchase #5	$33.35	12.830%	$37.6288	$37.63	$37.65	$37.60
Purchase #6	$54.67	5.825%	$57.8545	$57.85	$57.85	$57.90
Purchase #7	$86.62	11.488%	$96.5709	$96.57	$96.55	$96.60
7 purchase totals =	$856.10		$916.6855	$916.67	$916.65	$916.80