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	$185.54	8.315%	$200.9677	$200.97	$200.95	$201.00
Purchase #2	$41.37	3.739%	$42.9168	$42.92	$42.90	$42.90
Purchase #3	$206.57	13.114%	$233.6596	$233.66	$233.65	$233.70
Purchase #4	$172.69	13.515%	$196.0291	$196.03	$196.05	$196.00
Purchase #5	$159.45	9.430%	$174.4861	$174.49	$174.50	$174.50
Purchase #6	$87.40	4.503%	$91.3356	$91.34	$91.35	$91.30
Purchase #7	$216.63	13.575%	$246.0375	$246.04	$246.05	$246.00
7 purchase totals =	$1,069.65		$1,185.4324	$1,185.45	$1,185.45	$1,185.40