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	$199.59	11.229%	$222.002	$222.00	$222.00	$222.00
Purchase #2	$36.67	4.434%	$38.2959	$38.30	$38.30	$38.30
Purchase #3	$83.40	11.144%	$92.6941	$92.69	$92.70	$92.70
Purchase #4	$115.33	3.768%	$119.6756	$119.68	$119.70	$119.70
Purchase #5	$182.72	9.813%	$200.6503	$200.65	$200.65	$200.70
Purchase #6	$81.59	5.602%	$86.1607	$86.16	$86.15	$86.20
Purchase #7	$216.27	3.196%	$223.182	$223.18	$223.20	$223.20
7 purchase totals =	$915.57		$982.6606	$982.66	$982.70	$982.80