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	$186.55	13.390%	$211.529	$211.53	$211.55	$211.50
Purchase #2	$40.94	11.109%	$45.488	$45.49	$45.50	$45.50
Purchase #3	$79.86	6.529%	$85.0741	$85.07	$85.05	$85.10
Purchase #4	$239.88	10.573%	$265.2425	$265.24	$265.25	$265.20
Purchase #5	$65.51	10.176%	$72.1763	$72.18	$72.20	$72.20
Purchase #6	$112.51	3.462%	$116.4051	$116.41	$116.40	$116.40
Purchase #7	$181.81	13.316%	$206.0198	$206.02	$206.00	$206.00
7 purchase totals =	$907.06		$1,001.9348	$1,001.94	$1,001.95	$1,001.90