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	$48.57	9.409%	$53.14	$53.14	$53.15	$53.10
Purchase #2	$221.69	9.595%	$242.9612	$242.96	$242.95	$243.00
Purchase #3	$178.45	10.134%	$196.5341	$196.53	$196.55	$196.50
Purchase #4	$242.75	8.593%	$263.6095	$263.61	$263.60	$263.60
Purchase #5	$202.37	10.177%	$222.9652	$222.97	$222.95	$223.00
Purchase #6	$126.95	13.116%	$143.6008	$143.60	$143.60	$143.60
Purchase #7	$230.38	8.281%	$249.4578	$249.46	$249.45	$249.50
7 purchase totals =	$1,251.16		$1,372.2686	$1,372.27	$1,372.25	$1,372.30