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	$192.89	9.388%	$210.9985	$211.00	$211.00	$211.00
Purchase #2	$61.98	7.753%	$66.7853	$66.79	$66.80	$66.80
Purchase #3	$242.33	6.577%	$258.268	$258.27	$258.25	$258.30
Purchase #4	$85.74	4.421%	$89.5306	$89.53	$89.55	$89.50
Purchase #5	$237.80	3.324%	$245.7045	$245.70	$245.70	$245.70
Purchase #6	$99.88	5.450%	$105.3235	$105.32	$105.30	$105.30
Purchase #7	$67.92	13.172%	$76.8664	$76.87	$76.85	$76.90
7 purchase totals =	$988.54		$1,053.4768	$1,053.48	$1,053.45	$1,053.50