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	$196.84	7.202%	$211.0164	$211.02	$211.00	$211.00
Purchase #2	$172.49	7.338%	$185.1473	$185.15	$185.15	$185.10
Purchase #3	$64.29	10.266%	$70.89	$70.89	$70.90	$70.90
Purchase #4	$199.49	8.403%	$216.2531	$216.25	$216.25	$216.30
Purchase #5	$100.78	4.821%	$105.6386	$105.64	$105.65	$105.60
Purchase #6	$32.59	11.258%	$36.259	$36.26	$36.25	$36.30
Purchase #7	$94.48	7.651%	$101.7087	$101.71	$101.70	$101.70
7 purchase totals =	$860.96		$926.9131	$926.92	$926.90	$926.90