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	$60.42	7.692%	$65.0675	$65.07	$65.05	$65.10
Purchase #2	$21.44	6.564%	$22.8473	$22.85	$22.85	$22.80
Purchase #3	$54.56	9.188%	$59.573	$59.57	$59.55	$59.60
Purchase #4	$7.51	5.799%	$7.9455	$7.95	$7.95	$7.90
Purchase #5	$78.54	13.364%	$89.0361	$89.04	$89.05	$89.00
Purchase #6	$200.49	7.602%	$215.7312	$215.73	$215.75	$215.70
Purchase #7	$149.26	7.736%	$160.8068	$160.81	$160.80	$160.80
7 purchase totals =	$572.22		$621.0074	$621.02	$621.00	$620.90