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	$144.43	11.352%	$160.8257	$160.83	$160.85	$160.80
Purchase #2	$222.85	10.828%	$246.9802	$246.98	$247.00	$247.00
Purchase #3	$155.97	10.625%	$172.5418	$172.54	$172.55	$172.50
Purchase #4	$40.83	13.609%	$46.3866	$46.39	$46.40	$46.40
Purchase #5	$196.86	3.427%	$203.6064	$203.61	$203.60	$203.60
Purchase #6	$53.39	5.496%	$56.3243	$56.32	$56.30	$56.30
Purchase #7	$118.38	13.440%	$134.2903	$134.29	$134.30	$134.30
7 purchase totals =	$932.71		$1,020.9553	$1,020.96	$1,021.00	$1,020.90