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	$165.28	11.510%	$184.3037	$184.30	$184.30	$184.30
Purchase #2	$12.44	8.799%	$13.5346	$13.53	$13.55	$13.50
Purchase #3	$168.70	9.758%	$185.1617	$185.16	$185.15	$185.20
Purchase #4	$139.35	6.616%	$148.5694	$148.57	$148.55	$148.60
Purchase #5	$147.34	13.653%	$167.4563	$167.46	$167.45	$167.50
Purchase #6	$207.62	4.746%	$217.4736	$217.47	$217.45	$217.50
Purchase #7	$155.95	7.657%	$167.8911	$167.89	$167.90	$167.90
7 purchase totals =	$996.68		$1,084.3904	$1,084.38	$1,084.35	$1,084.50