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	$47.93	12.151%	$53.754	$53.75	$53.75	$53.80
Purchase #2	$144.33	5.408%	$152.1354	$152.14	$152.15	$152.10
Purchase #3	$210.75	11.534%	$235.0579	$235.06	$235.05	$235.10
Purchase #4	$80.48	11.812%	$89.9863	$89.99	$90.00	$90.00
Purchase #5	$205.79	11.469%	$229.3921	$229.39	$229.40	$229.40
Purchase #6	$145.37	4.103%	$151.3345	$151.33	$151.35	$151.30
Purchase #7	$118.91	3.550%	$123.1313	$123.13	$123.15	$123.10
7 purchase totals =	$953.56		$1,034.7915	$1,034.79	$1,034.85	$1,034.80