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	$163.42	7.229%	$175.2336	$175.23	$175.25	$175.20
Purchase #2	$64.94	4.523%	$67.8772	$67.88	$67.90	$67.90
Purchase #3	$38.31	13.703%	$43.5596	$43.56	$43.55	$43.60
Purchase #4	$147.56	5.762%	$156.0624	$156.06	$156.05	$156.10
Purchase #5	$235.83	7.805%	$254.2365	$254.24	$254.25	$254.20
Purchase #6	$162.42	12.693%	$183.036	$183.04	$183.05	$183.00
Purchase #7	$246.41	10.423%	$272.0933	$272.09	$272.10	$272.10
7 purchase totals =	$1,058.89		$1,152.0986	$1,152.10	$1,152.15	$1,152.10