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	$196.35	6.800%	$209.7018	$209.70	$209.70	$209.70
Purchase #2	$178.84	10.797%	$198.1494	$198.15	$198.15	$198.10
Purchase #3	$167.50	12.549%	$188.5196	$188.52	$188.50	$188.50
Purchase #4	$197.27	5.591%	$208.2994	$208.30	$208.30	$208.30
Purchase #5	$88.98	13.173%	$100.7013	$100.70	$100.70	$100.70
Purchase #6	$236.52	7.741%	$254.829	$254.83	$254.85	$254.80
Purchase #7	$224.76	13.132%	$254.2755	$254.28	$254.30	$254.30
7 purchase totals =	$1,290.22		$1,414.4760	$1,414.48	$1,414.50	$1,414.40