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	$141.31	7.552%	$151.9817	$151.98	$152.00	$152.00
Purchase #2	$232.58	9.451%	$254.5611	$254.56	$254.55	$254.60
Purchase #3	$243.93	7.666%	$262.6297	$262.63	$262.65	$262.60
Purchase #4	$9.32	6.284%	$9.9057	$9.91	$9.90	$9.90
Purchase #5	$68.55	5.800%	$72.5259	$72.53	$72.55	$72.50
Purchase #6	$12.92	3.297%	$13.346	$13.35	$13.35	$13.30
Purchase #7	$222.51	11.595%	$248.31	$248.31	$248.30	$248.30
7 purchase totals =	$931.12		$1,013.2601	$1,013.27	$1,013.30	$1,013.20