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	$185.66	5.603%	$196.0625	$196.06	$196.05	$196.10
Purchase #2	$172.71	13.627%	$196.2452	$196.25	$196.25	$196.20
Purchase #3	$213.29	7.533%	$229.3571	$229.36	$229.35	$229.40
Purchase #4	$160.81	3.534%	$166.493	$166.49	$166.50	$166.50
Purchase #5	$170.68	13.744%	$194.1383	$194.14	$194.15	$194.10
Purchase #6	$32.43	8.837%	$35.2958	$35.30	$35.30	$35.30
Purchase #7	$7.59	3.349%	$7.8442	$7.84	$7.85	$7.80
7 purchase totals =	$943.17		$1,025.4361	$1,025.44	$1,025.45	$1,025.40