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	$142.85	5.580%	$150.821	$150.82	$150.80	$150.80
Purchase #2	$33.42	13.472%	$37.9223	$37.92	$37.90	$37.90
Purchase #3	$190.79	13.139%	$215.8579	$215.86	$215.85	$215.90
Purchase #4	$70.41	9.656%	$77.2088	$77.21	$77.20	$77.20
Purchase #5	$249.49	10.297%	$275.18	$275.18	$275.20	$275.20
Purchase #6	$58.60	10.423%	$64.7079	$64.71	$64.70	$64.70
Purchase #7	$216.31	4.686%	$226.4463	$226.45	$226.45	$226.40
7 purchase totals =	$961.87		$1,048.1442	$1,048.15	$1,048.10	$1,048.10