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	$69.29	4.190%	$72.1933	$72.19	$72.20	$72.20
Purchase #2	$69.32	5.841%	$73.369	$73.37	$73.35	$73.40
Purchase #3	$74.57	12.284%	$83.7302	$83.73	$83.75	$83.70
Purchase #4	$74.55	5.215%	$78.4378	$78.44	$78.45	$78.40
Purchase #5	$105.27	10.432%	$116.2518	$116.25	$116.25	$116.30
Purchase #6	$146.62	13.134%	$165.8771	$165.88	$165.90	$165.90
Purchase #7	$158.49	6.269%	$168.4257	$168.43	$168.45	$168.40
7 purchase totals =	$698.11		$758.2849	$758.29	$758.35	$758.30