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	$163.60	9.745%	$179.5428	$179.54	$179.55	$179.50
Purchase #2	$161.40	8.711%	$175.4596	$175.46	$175.45	$175.50
Purchase #3	$177.36	10.608%	$196.1743	$196.17	$196.15	$196.20
Purchase #4	$187.34	11.627%	$209.122	$209.12	$209.10	$209.10
Purchase #5	$32.68	12.839%	$36.8758	$36.88	$36.90	$36.90
Purchase #6	$203.35	4.821%	$213.1535	$213.15	$213.15	$213.20
Purchase #7	$127.73	10.106%	$140.6384	$140.64	$140.65	$140.60
7 purchase totals =	$1,053.46		$1,150.9664	$1,150.96	$1,150.95	$1,151.00