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	$175.93	6.412%	$187.2106	$187.21	$187.20	$187.20
Purchase #2	$168.28	13.454%	$190.9204	$190.92	$190.90	$190.90
Purchase #3	$93.42	4.504%	$97.6276	$97.63	$97.65	$97.60
Purchase #4	$141.79	6.778%	$151.4005	$151.40	$151.40	$151.40
Purchase #5	$137.30	4.236%	$143.116	$143.12	$143.10	$143.10
Purchase #6	$182.37	7.773%	$196.5456	$196.55	$196.55	$196.50
Purchase #7	$125.47	11.218%	$139.5452	$139.55	$139.55	$139.50
7 purchase totals =	$1,024.56		$1,106.3659	$1,106.38	$1,106.35	$1,106.20