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	$167.45	10.342%	$184.7677	$184.77	$184.75	$184.80
Purchase #2	$96.34	8.516%	$104.5443	$104.54	$104.55	$104.50
Purchase #3	$126.54	8.571%	$137.3857	$137.39	$137.40	$137.40
Purchase #4	$147.99	3.680%	$153.436	$153.44	$153.45	$153.40
Purchase #5	$215.89	4.412%	$225.4151	$225.42	$225.40	$225.40
Purchase #6	$104.92	4.592%	$109.7379	$109.74	$109.75	$109.70
Purchase #7	$130.34	11.604%	$145.4647	$145.46	$145.45	$145.50
7 purchase totals =	$989.47		$1,060.7514	$1,060.76	$1,060.75	$1,060.70