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	$61.32	4.403%	$64.0199	$64.02	$64.00	$64.00
Purchase #2	$173.33	5.548%	$182.9463	$182.95	$182.95	$182.90
Purchase #3	$213.47	5.530%	$225.2749	$225.27	$225.25	$225.30
Purchase #4	$204.67	12.790%	$230.8473	$230.85	$230.85	$230.80
Purchase #5	$83.88	3.480%	$86.799	$86.80	$86.80	$86.80
Purchase #6	$137.74	13.540%	$156.39	$156.39	$156.40	$156.40
Purchase #7	$64.48	12.123%	$72.2969	$72.30	$72.30	$72.30
7 purchase totals =	$938.89		$1,018.5743	$1,018.58	$1,018.55	$1,018.50