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	$207.55	10.681%	$229.7184	$229.72	$229.70	$229.70
Purchase #2	$200.28	5.516%	$211.3274	$211.33	$211.35	$211.30
Purchase #3	$57.54	3.735%	$59.6891	$59.69	$59.70	$59.70
Purchase #4	$151.67	4.522%	$158.5285	$158.53	$158.55	$158.50
Purchase #5	$65.79	8.480%	$71.369	$71.37	$71.35	$71.40
Purchase #6	$134.77	9.494%	$147.5651	$147.57	$147.55	$147.60
Purchase #7	$137.36	6.446%	$146.2142	$146.21	$146.20	$146.20
7 purchase totals =	$954.96		$1,024.4117	$1,024.42	$1,024.40	$1,024.40