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	$62.44	11.705%	$69.7486	$69.75	$69.75	$69.70
Purchase #2	$99.96	13.391%	$113.3456	$113.35	$113.35	$113.30
Purchase #3	$36.67	3.451%	$37.9355	$37.94	$37.95	$37.90
Purchase #4	$193.80	10.474%	$214.0986	$214.10	$214.10	$214.10
Purchase #5	$70.25	3.829%	$72.9399	$72.94	$72.95	$72.90
Purchase #6	$57.57	6.738%	$61.4491	$61.45	$61.45	$61.40
Purchase #7	$44.29	3.422%	$45.8056	$45.81	$45.80	$45.80
7 purchase totals =	$564.98		$615.3229	$615.34	$615.35	$615.10