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	$82.61	11.320%	$91.9615	$91.96	$91.95	$92.00
Purchase #2	$236.95	9.395%	$259.2115	$259.21	$259.20	$259.20
Purchase #3	$33.61	10.126%	$37.0133	$37.01	$37.00	$37.00
Purchase #4	$40.98	11.138%	$45.5444	$45.54	$45.55	$45.50
Purchase #5	$217.63	11.163%	$241.924	$241.92	$241.90	$241.90
Purchase #6	$110.80	13.192%	$125.4167	$125.42	$125.40	$125.40
Purchase #7	$90.85	9.531%	$99.5089	$99.51	$99.50	$99.50
7 purchase totals =	$813.43		$900.5803	$900.57	$900.50	$900.50