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	$219.66	4.189%	$228.8616	$228.86	$228.85	$228.90
Purchase #2	$205.36	9.769%	$225.4216	$225.42	$225.40	$225.40
Purchase #3	$194.51	9.591%	$213.1655	$213.17	$213.15	$213.20
Purchase #4	$45.38	9.583%	$49.7288	$49.73	$49.75	$49.70
Purchase #5	$162.92	11.302%	$181.3332	$181.33	$181.35	$181.30
Purchase #6	$135.54	12.560%	$152.5638	$152.56	$152.55	$152.60
Purchase #7	$53.72	10.546%	$59.3853	$59.39	$59.40	$59.40
7 purchase totals =	$1,017.09		$1,110.4598	$1,110.46	$1,110.45	$1,110.50