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	$172.41	9.318%	$188.4752	$188.48	$188.50	$188.50
Purchase #2	$223.86	10.566%	$247.513	$247.51	$247.50	$247.50
Purchase #3	$13.29	11.663%	$14.84	$14.84	$14.85	$14.80
Purchase #4	$187.82	4.511%	$196.2926	$196.29	$196.30	$196.30
Purchase #5	$162.27	10.327%	$179.0276	$179.03	$179.05	$179.00
Purchase #6	$28.67	5.764%	$30.3225	$30.32	$30.30	$30.30
Purchase #7	$192.50	3.673%	$199.5705	$199.57	$199.55	$199.60
7 purchase totals =	$980.82		$1,056.0414	$1,056.04	$1,056.05	$1,056.00