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	$193.99	7.390%	$208.3259	$208.33	$208.35	$208.30
Purchase #2	$198.85	6.852%	$212.4752	$212.48	$212.50	$212.50
Purchase #3	$135.30	11.554%	$150.9326	$150.93	$150.95	$150.90
Purchase #4	$64.58	4.663%	$67.5914	$67.59	$67.60	$67.60
Purchase #5	$43.95	4.205%	$45.7981	$45.80	$45.80	$45.80
Purchase #6	$173.53	6.199%	$184.2871	$184.29	$184.30	$184.30
Purchase #7	$134.33	7.426%	$144.3053	$144.31	$144.30	$144.30
7 purchase totals =	$944.53		$1,013.7156	$1,013.73	$1,013.80	$1,013.70