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	$183.98	6.827%	$196.5403	$196.54	$196.55	$196.50
Purchase #2	$30.31	7.817%	$32.6793	$32.68	$32.70	$32.70
Purchase #3	$40.96	4.714%	$42.8909	$42.89	$42.90	$42.90
Purchase #4	$176.27	5.630%	$186.194	$186.19	$186.20	$186.20
Purchase #5	$185.39	5.534%	$195.6495	$195.65	$195.65	$195.60
Purchase #6	$248.65	6.482%	$264.7675	$264.77	$264.75	$264.80
Purchase #7	$143.83	11.205%	$159.9462	$159.95	$159.95	$159.90
7 purchase totals =	$1,009.39		$1,078.6677	$1,078.67	$1,078.70	$1,078.60