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	$238.98	9.858%	$262.5386	$262.54	$262.55	$262.50
Purchase #2	$200.93	11.356%	$223.7476	$223.75	$223.75	$223.70
Purchase #3	$81.52	6.690%	$86.9737	$86.97	$86.95	$87.00
Purchase #4	$69.25	5.255%	$72.8891	$72.89	$72.90	$72.90
Purchase #5	$162.37	13.479%	$184.2559	$184.26	$184.25	$184.30
Purchase #6	$25.44	11.352%	$28.3279	$28.33	$28.35	$28.30
Purchase #7	$147.41	5.300%	$155.2227	$155.22	$155.20	$155.20
7 purchase totals =	$925.90		$1,013.9555	$1,013.96	$1,013.95	$1,013.90