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	$193.96	3.623%	$200.9872	$200.99	$201.00	$201.00
Purchase #2	$249.91	7.423%	$268.4608	$268.46	$268.45	$268.50
Purchase #3	$53.45	5.684%	$56.4881	$56.49	$56.50	$56.50
Purchase #4	$231.90	11.868%	$259.4219	$259.42	$259.40	$259.40
Purchase #5	$91.42	8.359%	$99.0618	$99.06	$99.05	$99.10
Purchase #6	$222.82	4.381%	$232.5817	$232.58	$232.60	$232.60
Purchase #7	$123.33	3.474%	$127.6145	$127.61	$127.60	$127.60
7 purchase totals =	$1,166.79		$1,244.6160	$1,244.61	$1,244.60	$1,244.70