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	$213.67	11.531%	$238.3083	$238.31	$238.30	$238.30
Purchase #2	$105.35	5.767%	$111.4255	$111.43	$111.45	$111.40
Purchase #3	$195.37	13.472%	$221.6902	$221.69	$221.70	$221.70
Purchase #4	$130.45	4.649%	$136.5146	$136.51	$136.50	$136.50
Purchase #5	$62.38	7.483%	$67.0479	$67.05	$67.05	$67.00
Purchase #6	$147.34	6.183%	$156.45	$156.45	$156.45	$156.50
Purchase #7	$80.58	12.626%	$90.754	$90.75	$90.75	$90.80
7 purchase totals =	$935.14		$1,022.1905	$1,022.19	$1,022.20	$1,022.20