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	$67.37	7.355%	$72.3251	$72.33	$72.35	$72.30
Purchase #2	$196.87	9.552%	$215.675	$215.68	$215.70	$215.70
Purchase #3	$222.88	9.592%	$244.2586	$244.26	$244.25	$244.30
Purchase #4	$136.48	4.388%	$142.4687	$142.47	$142.45	$142.50
Purchase #5	$128.87	6.442%	$137.1718	$137.17	$137.15	$137.20
Purchase #6	$75.76	12.273%	$85.058	$85.06	$85.05	$85.10
Purchase #7	$193.83	11.253%	$215.6417	$215.64	$215.65	$215.60
7 purchase totals =	$1,022.06		$1,112.5989	$1,112.61	$1,112.60	$1,112.70