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	$154.75	11.590%	$172.6855	$172.69	$172.70	$172.70
Purchase #2	$118.61	3.754%	$123.0626	$123.06	$123.05	$123.10
Purchase #3	$49.27	8.648%	$53.5309	$53.53	$53.55	$53.50
Purchase #4	$175.53	3.789%	$182.1808	$182.18	$182.20	$182.20
Purchase #5	$135.92	5.458%	$143.3385	$143.34	$143.35	$143.30
Purchase #6	$216.49	12.857%	$244.3241	$244.32	$244.30	$244.30
Purchase #7	$163.73	11.362%	$182.333	$182.33	$182.35	$182.30
7 purchase totals =	$1,014.30		$1,101.4554	$1,101.45	$1,101.50	$1,101.40