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	$194.63	10.367%	$214.8073	$214.81	$214.80	$214.80
Purchase #2	$111.47	11.557%	$124.3526	$124.35	$124.35	$124.40
Purchase #3	$145.66	9.805%	$159.942	$159.94	$159.95	$159.90
Purchase #4	$191.87	11.217%	$213.3921	$213.39	$213.40	$213.40
Purchase #5	$175.56	11.865%	$196.3902	$196.39	$196.40	$196.40
Purchase #6	$35.34	9.806%	$38.8054	$38.81	$38.80	$38.80
Purchase #7	$163.52	10.104%	$180.0421	$180.04	$180.05	$180.00
7 purchase totals =	$1,018.05		$1,127.7317	$1,127.73	$1,127.75	$1,127.70