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	$173.86	13.289%	$196.9643	$196.96	$196.95	$197.00
Purchase #2	$198.59	11.860%	$222.1428	$222.14	$222.15	$222.10
Purchase #3	$118.79	5.207%	$124.9754	$124.98	$125.00	$125.00
Purchase #4	$238.53	11.152%	$265.1309	$265.13	$265.15	$265.10
Purchase #5	$118.51	11.489%	$132.1256	$132.13	$132.15	$132.10
Purchase #6	$56.42	10.111%	$62.1246	$62.12	$62.10	$62.10
Purchase #7	$85.59	7.349%	$91.88	$91.88	$91.90	$91.90
7 purchase totals =	$990.29		$1,095.3436	$1,095.34	$1,095.40	$1,095.30