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	$108.94	3.821%	$113.1026	$113.10	$113.10	$113.10
Purchase #2	$144.92	5.102%	$152.3138	$152.31	$152.30	$152.30
Purchase #3	$184.68	6.416%	$196.5291	$196.53	$196.55	$196.50
Purchase #4	$139.95	12.434%	$157.3514	$157.35	$157.35	$157.40
Purchase #5	$38.76	13.208%	$43.8794	$43.88	$43.90	$43.90
Purchase #6	$233.79	9.581%	$256.1894	$256.19	$256.20	$256.20
Purchase #7	$104.41	12.585%	$117.55	$117.55	$117.55	$117.60
7 purchase totals =	$955.45		$1,036.9157	$1,036.91	$1,036.95	$1,037.00