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	$234.60	4.626%	$245.4526	$245.45	$245.45	$245.50
Purchase #2	$43.88	6.817%	$46.8713	$46.87	$46.85	$46.90
Purchase #3	$55.90	7.192%	$59.9203	$59.92	$59.90	$59.90
Purchase #4	$250.31	5.327%	$263.644	$263.64	$263.65	$263.60
Purchase #5	$201.39	5.252%	$211.967	$211.97	$211.95	$212.00
Purchase #6	$113.53	4.172%	$118.2665	$118.27	$118.25	$118.30
Purchase #7	$53.65	8.743%	$58.3406	$58.34	$58.35	$58.30
7 purchase totals =	$953.26		$1,004.4623	$1,004.46	$1,004.40	$1,004.50