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	$141.52	7.422%	$152.0236	$152.02	$152.00	$152.00
Purchase #2	$51.33	13.790%	$58.4084	$58.41	$58.40	$58.40
Purchase #3	$130.89	13.175%	$148.1348	$148.13	$148.15	$148.10
Purchase #4	$166.37	11.458%	$185.4327	$185.43	$185.45	$185.40
Purchase #5	$96.90	3.272%	$100.0706	$100.07	$100.05	$100.10
Purchase #6	$216.83	13.489%	$246.0782	$246.08	$246.10	$246.10
Purchase #7	$222.70	4.565%	$232.8663	$232.87	$232.85	$232.90
7 purchase totals =	$1,026.54		$1,123.0146	$1,123.01	$1,123.00	$1,123.00