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	$181.96	7.469%	$195.5506	$195.55	$195.55	$195.60
Purchase #2	$53.35	11.749%	$59.6181	$59.62	$59.60	$59.60
Purchase #3	$66.35	12.448%	$74.6092	$74.61	$74.60	$74.60
Purchase #4	$173.31	13.360%	$196.4642	$196.46	$196.45	$196.50
Purchase #5	$105.58	3.591%	$109.3714	$109.37	$109.35	$109.40
Purchase #6	$12.45	13.322%	$14.1086	$14.11	$14.10	$14.10
Purchase #7	$190.81	4.284%	$198.9843	$198.98	$199.00	$199.00
7 purchase totals =	$783.81		$848.7064	$848.70	$848.65	$848.80