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	$147.59	5.663%	$155.948	$155.95	$155.95	$155.90
Purchase #2	$86.80	3.818%	$90.114	$90.11	$90.10	$90.10
Purchase #3	$167.62	8.633%	$182.0906	$182.09	$182.10	$182.10
Purchase #4	$212.55	12.623%	$239.3802	$239.38	$239.40	$239.40
Purchase #5	$245.33	4.240%	$255.732	$255.73	$255.75	$255.70
Purchase #6	$79.69	8.597%	$86.5409	$86.54	$86.55	$86.50
Purchase #7	$132.97	13.392%	$150.7773	$150.78	$150.80	$150.80
7 purchase totals =	$1,072.55		$1,160.5830	$1,160.58	$1,160.65	$1,160.50