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	$191.50	9.645%	$209.9702	$209.97	$209.95	$210.00
Purchase #2	$77.71	5.140%	$81.7043	$81.70	$81.70	$81.70
Purchase #3	$165.90	3.333%	$171.4294	$171.43	$171.45	$171.40
Purchase #4	$138.90	5.220%	$146.1506	$146.15	$146.15	$146.20
Purchase #5	$134.69	13.334%	$152.6496	$152.65	$152.65	$152.60
Purchase #6	$160.94	10.834%	$178.3762	$178.38	$178.40	$178.40
Purchase #7	$59.59	7.857%	$64.272	$64.27	$64.25	$64.30
7 purchase totals =	$929.23		$1,004.5523	$1,004.55	$1,004.55	$1,004.60