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	$141.63	7.853%	$152.7522	$152.75	$152.75	$152.80
Purchase #2	$98.47	6.172%	$104.5476	$104.55	$104.55	$104.50
Purchase #3	$181.45	5.187%	$190.8618	$190.86	$190.85	$190.90
Purchase #4	$230.61	4.240%	$240.3879	$240.39	$240.40	$240.40
Purchase #5	$210.61	6.115%	$223.4888	$223.49	$223.50	$223.50
Purchase #6	$51.30	5.376%	$54.0579	$54.06	$54.05	$54.10
Purchase #7	$137.91	4.841%	$144.5862	$144.59	$144.60	$144.60
7 purchase totals =	$1,051.98		$1,110.6824	$1,110.69	$1,110.70	$1,110.80