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	$208.74	7.280%	$223.9363	$223.94	$223.95	$223.90
Purchase #2	$75.94	6.584%	$80.9399	$80.94	$80.95	$80.90
Purchase #3	$168.99	8.224%	$182.8877	$182.89	$182.90	$182.90
Purchase #4	$190.48	3.140%	$196.4611	$196.46	$196.45	$196.50
Purchase #5	$92.37	7.854%	$99.6247	$99.62	$99.60	$99.60
Purchase #6	$161.55	4.266%	$168.4417	$168.44	$168.45	$168.40
Purchase #7	$62.60	13.797%	$71.2369	$71.24	$71.25	$71.20
7 purchase totals =	$960.67		$1,023.5283	$1,023.53	$1,023.55	$1,023.40