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	$174.43	4.243%	$181.8311	$181.83	$181.85	$181.80
Purchase #2	$149.96	12.424%	$168.591	$168.59	$168.60	$168.60
Purchase #3	$73.42	11.801%	$82.0843	$82.08	$82.10	$82.10
Purchase #4	$161.38	12.208%	$181.0813	$181.08	$181.10	$181.10
Purchase #5	$95.27	4.421%	$99.4819	$99.48	$99.50	$99.50
Purchase #6	$188.88	9.563%	$206.9426	$206.94	$206.95	$206.90
Purchase #7	$214.93	12.394%	$241.5684	$241.57	$241.55	$241.60
7 purchase totals =	$1,058.27		$1,161.5806	$1,161.57	$1,161.65	$1,161.60