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	$185.63	5.140%	$195.1714	$195.17	$195.15	$195.20
Purchase #2	$120.67	4.800%	$126.4622	$126.46	$126.45	$126.50
Purchase #3	$45.42	12.825%	$51.2451	$51.25	$51.25	$51.20
Purchase #4	$63.29	3.399%	$65.4412	$65.44	$65.45	$65.40
Purchase #5	$185.41	3.506%	$191.9105	$191.91	$191.90	$191.90
Purchase #6	$94.57	9.114%	$103.1891	$103.19	$103.20	$103.20
Purchase #7	$127.28	3.604%	$131.8672	$131.87	$131.85	$131.90
7 purchase totals =	$822.27		$865.2867	$865.29	$865.25	$865.30