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	$228.38	7.508%	$245.5268	$245.53	$245.55	$245.50
Purchase #2	$204.33	5.455%	$215.4762	$215.48	$215.50	$215.50
Purchase #3	$37.57	8.140%	$40.6282	$40.63	$40.65	$40.60
Purchase #4	$101.76	3.296%	$105.114	$105.11	$105.10	$105.10
Purchase #5	$185.79	3.838%	$192.9206	$192.92	$192.90	$192.90
Purchase #6	$53.28	9.196%	$58.1796	$58.18	$58.20	$58.20
Purchase #7	$197.52	13.444%	$224.0746	$224.07	$224.05	$224.10
7 purchase totals =	$1,008.63		$1,081.9200	$1,081.92	$1,081.95	$1,081.90