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	$177.61	9.307%	$194.1402	$194.14	$194.15	$194.10
Purchase #2	$11.38	11.829%	$12.7261	$12.73	$12.75	$12.70
Purchase #3	$222.88	11.460%	$248.422	$248.42	$248.40	$248.40
Purchase #4	$196.83	13.708%	$223.8115	$223.81	$223.80	$223.80
Purchase #5	$85.93	3.477%	$88.9178	$88.92	$88.90	$88.90
Purchase #6	$212.32	7.843%	$228.9723	$228.97	$228.95	$229.00
Purchase #7	$187.54	4.809%	$196.5588	$196.56	$196.55	$196.60
7 purchase totals =	$1,094.49		$1,193.5487	$1,193.55	$1,193.50	$1,193.50