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	$193.40	5.812%	$204.6404	$204.64	$204.65	$204.60
Purchase #2	$183.81	8.842%	$200.0625	$200.06	$200.05	$200.10
Purchase #3	$156.79	5.624%	$165.6079	$165.61	$165.60	$165.60
Purchase #4	$158.89	13.132%	$179.7554	$179.76	$179.75	$179.80
Purchase #5	$105.87	5.730%	$111.9364	$111.94	$111.95	$111.90
Purchase #6	$164.65	9.173%	$179.7533	$179.75	$179.75	$179.80
Purchase #7	$151.30	5.308%	$159.331	$159.33	$159.35	$159.30
7 purchase totals =	$1,114.71		$1,201.0869	$1,201.09	$1,201.10	$1,201.10