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	$181.47	7.440%	$194.9714	$194.97	$194.95	$195.00
Purchase #2	$105.86	3.309%	$109.3629	$109.36	$109.35	$109.40
Purchase #3	$217.74	13.631%	$247.4201	$247.42	$247.40	$247.40
Purchase #4	$95.42	8.478%	$103.5097	$103.51	$103.50	$103.50
Purchase #5	$217.74	7.479%	$234.0248	$234.02	$234.00	$234.00
Purchase #6	$101.77	11.709%	$113.6862	$113.69	$113.70	$113.70
Purchase #7	$82.33	3.794%	$85.4536	$85.45	$85.45	$85.50
7 purchase totals =	$1,002.33		$1,088.4287	$1,088.42	$1,088.35	$1,088.50