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	$196.70	7.179%	$210.8211	$210.82	$210.80	$210.80
Purchase #2	$62.97	5.436%	$66.393	$66.39	$66.40	$66.40
Purchase #3	$42.58	10.420%	$47.0168	$47.02	$47.00	$47.00
Purchase #4	$236.84	12.279%	$265.9216	$265.92	$265.90	$265.90
Purchase #5	$211.39	8.297%	$228.929	$228.93	$228.95	$228.90
Purchase #6	$104.64	13.492%	$118.758	$118.76	$118.75	$118.80
Purchase #7	$94.39	5.459%	$99.5428	$99.54	$99.55	$99.50
7 purchase totals =	$949.51		$1,037.3823	$1,037.38	$1,037.35	$1,037.30